Apparatuses and methods for producing covetic materials using microwave reactors

ABSTRACT

Apparatuses and methods for producing covetic materials by exciting a hydrocarbon gas with pulse microwaves to form hydrocarbon radicals in a hot first region of a microwave reactor. Graphene nanoplatelets are formed by the nucleation, growth and assembly of the hydrocarbon radicals, and contact a metal melt introduced downstream of the hot region to produce a mixture of molten metal and graphene nanoplatelets which assemble in-flight to form covetic materials. Graphene planes are infused in the metal matrix to achieve carbon loadings of at least 60%.

RELATED APPLICATIONS

This Patent Application is a continuation application of U.S. patentapplication Ser. No. 17/241,852 entitled “APPARATUSES AND METHODS FORPRODUCING COVETIC MATERIALS USING MICROWAVE REACTORS” and filed on Apr.27, 2021, which is a divisional application of U.S. patent applicationSer. No. 16/752,693 entitled “COVETIC MATERIALS” and filed on Jan. 27,2020, which is a continuation in part of U.S. patent application Ser.No. 16/460,177 entitled “PLASMA SPRAY SYSTEMS AND METHODS” and filed onJul. 2, 2019, which claims priority to U.S. Provisional PatentApplication No. 62/720,677 entitled “PLASMA SPRAY SYSTEMS AND METHODS”and filed on Aug. 21, 2018, to U.S. Provisional Patent Application No.62/714,030 entitled “PLASMA SPRAY DEPOSITION” and filed on Aug. 2, 2018,to U.S. Provisional Patent Application No. 62/903,649 filed on Sep. 20,2019, to U.S. Provisional Patent Application No. 62/868,493 filed onJun. 28, 2019, to U.S. Provisional Patent Application No. 62/839,995filed on Apr. 29, 2019, and to U.S. Provisional Patent Application No.62/797,306 filed on Jan. 27, 2019. The disclosures of all priorApplications are considered part of and are incorporated by reference inthis Patent Application.

TECHNICAL FIELD

This disclosure generally relates to making and using covetic materials.

BACKGROUND

The term covetic materials refers to metals infused with nanoscale-sizedcarbon particles. Covetic materials are desired in various applicationssince covetic materials possess many physical, chemical, and electricalproperties that exceed the capabilities of traditional non-carboninfused materials. Moreover, covetic materials that derive fromconventional covetic material generation techniques fail to achieve manyof the aforementioned physical, chemical, and electrical properties.

Even in the face of strong demand for materials that exhibit theaforementioned physical, chemical, and electrical properties, manytechnical challenges have impeded development of techniques for makingand using covetic materials. These technical challenges have arisen inmultiple areas, including: (1) difficulties in combining analyticalmethods needed to measure carbon content and the characterization of themicro- or nano-structures of individual compounds with a high degree ofspecificity; (2) relatively high variability of carbon contentdistribution in samples produced thus far; (3) variability and potentialunpredictability in property measurements; (4) uncertainties concerningthe exact scientific mechanisms responsible for the observed strongbonding between carbon particles and their surrounding matrix.

Conventional metal melting methods used to produce covetic carbon-metalcomposite alloys suffer from inconsistent conversion yields,contributing to the observed wide variations in resultant materialproperties. For instance, unwanted formation of agglomerates andunwanted clustering often occurs due to irregularities in dispersion ofcarbon in the melt. Such irregularities in dispersion of carbon in themetal can lead to formation of cracks and pores that ultimately causepremature failure of the resultant material. Further, the highsolubility of carbon in a metal may result in non-uniform (such asthicker) carbon growth at the surface of the metal as the metal coolsand solidifies. Additionally, solubility of carbon may be higher near afree surface than in the bulk of the metal, where higher solubilitycombined with interfacial energy at the melt-air interface favorsundesirable precipitation at the melt-air interface.

Conventional thermal-based metal melting methods to produce coveticcarbon-metal composite alloys currently cannot facilitate tuning ofprocess conditions such that the resultant covetic materials exhibit aset of desirable tuned or target properties. An inability to controlprocess conditions such that the resultant covetic materials exhibit aset of tuned properties leads to (a corresponding) an inability to applycovetic materials to specific uses that demand such specific sets ofproperties. What is needed are techniques to produce resultant coveticmaterials that exhibit a range of tunable properties. Furthermore, whatis needed are resultant covetic materials that that can be used in widerange of end-use areas and applications (such as business-to-business orconsumer uses, ranging from material strengthening to longevityperformance enhancements, etc.)

SUMMARY

This Summary is provided to introduce in a simplified form a selectionof concepts that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tolimit the scope of the claimed subject matter. Moreover, the systems,methods and devices of this disclosure each have several innovativeaspects, no single one of which is solely responsible for the desirableattributes disclosed herein.

Various implementations of the subject matter disclosed herein relategenerally to apparatuses, methods and various compositions ofcarbon-metal composite materials. The apparatuses are shown anddiscussed as may be relevant to controlled usage of a plasma spray torchapparatus to produce various carbon-metal bonded compositions of matter,referred to generally and in the present disclosure as “coveticmaterials”.

One configuration of a plasma spray torch is embodied as apparatushaving a reaction chamber configured to receive a hydrocarbon processgas that is mixed with a plurality of molten metal nanoscale-sizedparticles, a microwave energy source operatively coupled to the reactionchamber to provide power thereto, and a controller to adjust themicrowave energy source to create conditions in the reaction chambersuch that the hydrocarbon process gas dissociates into its constituentcarbon atoms, and single layer graphene (SLG) or few layer graphene(FLG) is grown from the carbon atoms onto the molten metalnanoscale-sized particles to form a plurality of carbon-metalnanoscale-sized particles. In some configurations, the conditions in thereaction chamber cause: (i) a first temperature at which the carbonatoms dissolve into the molten metal nanoscale-sized particles, and (ii)a second temperature at which at least some of the dissolved carbonatoms combine with the molten metal in a crystallographic configuration.Some configurations of the apparatus avail of a cooling zone to cool theplurality of carbon-metal nanoscale-sized particles to a powdered formthat can be collected and stored in a containment vessel that isjuxtaposed in proximity with the reaction chamber.

Details of one or more implementations of the subject matter describedin this disclosure are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations of the subject matter disclosed herein are illustratedby way of example and are not intended to be limited by the figures ofthe accompanying drawings. Like numbers reference like elementsthroughout the drawings and specification. Note that the relativedimensions of the following figures may not be drawn to scale.

FIG. 1A is a comparison chart showing two different covetic materialformation techniques and example materials that result from applicationof each, respectively, according to some implementations.

FIG. 1B presents a high-resolution transmission electron microscopyimage and a high-resolution energy dispersive spectroscopy x-ray image,according to some implementations.

FIG. 2 depicts a manufacturing process for growing graphene onto smallmolten particles, in accordance with one or more of the disclosedimplementations.

FIG. 3 depicts a plasma energy state chart showing how a pulsedmicrowave energy source is used for growing graphene onto small moltenparticles, in accordance with one or more of the disclosedimplementations.

FIG. 4 depicts an electron temperature control technique that is usedfor growing graphene onto small molten particles, in accordance with oneor more of the disclosed implementations.

FIG. 5 illustrates a dual plasma torch apparatus that is used forgrowing graphene onto small molten particles, in accordance with one ormore of the disclosed implementations.

FIG. 6 illustrates a pulsed microwave plasma spray torch apparatus thatis tuned for growing graphene onto small molten particles, in accordancewith one or more of the disclosed implementations.

FIG. 7 is a diagram depicting the intersection of common subject matterareas associated with covetics (or related materials), plasma torchspraying, and/or robust synthesized complex carbon coatings, inaccordance with one or more of the disclosed implementations.

FIGS. 8A-B are schematics depicting plasma spray processes that are usedfor spraying carbon particles onto small molten particles, in accordancewith one or more of the disclosed implementations.

FIG. 9 is a scanning electron microscope image showing the effect ofspraying carbon particles onto small molten particles, in accordancewith one or more of the disclosed implementations.

FIG. 10 shows a chart depicting a graphene growth temperature profileand a binary phase diagram, in accordance with one or more of thedisclosed implementations.

FIG. 11 is a cross-section view of a plasma flame apparatus, inaccordance with one or more of the disclosed implementations.

FIG. 12 depicts a pulsed microwave process flow that is used whengrowing graphene onto small molten particles, in accordance with one ormore of the disclosed implementations.

FIG. 13 is a perspective view of a pulsed microwave plasma spraywaveguide apparatus that is used for growing graphene onto small moltenparticles, in accordance with one or more of the disclosedimplementations.

FIG. 14 is a schematic depiction of a micro-welding technique that isused for growing graphene onto small molten particles, in accordancewith one or more of the disclosed implementations.

FIG. 15 is a schematic depiction of a plasma spray apparatus in acoaxial configuration, in accordance with one or more of the disclosedimplementations.

FIG. 16 is a schematic depiction of a plasma spray apparatus showing theevolution of materials by processing through a series of non-equilibriumenergy conditions, in accordance with one or more of the disclosedimplementations.

FIG. 17 depicts a surface wave plasma system for growing graphene ontomolten particles, in accordance with one or more of the disclosedimplementations.

FIG. 18A1-2, FIG. 18B, FIG. 18C, and FIG. 18D depict variousconfigurations of a plasma spray reactor, in accordance with one or moreof the disclosed implementations.

FIG. 19 is a chart that depicts energy versus time during pulse on andpulse off, in accordance with one or more of the disclosedimplementations.

FIG. 20A1 are images depicting organo-metallic bonding that occurs whencombining carbon and copper using a plasma spray torch, in accordancewith some of the disclosed implementations.

FIG. 20A2 are images depicting a graded composition of matter appliedinto a substrate material and showing multiple (such as three) materialproperty zones, in accordance with some of the disclosedimplementations.

FIG. 20B is a materials evolution chart depicting several layeredconfigurations that occur when adding carbon to bulk aluminum, inaccordance with one or more of the disclosed implementations.

FIG. 21A depicts an apparatus for spraying a molten mixture of materialsinto a substrate, according to an implementation.

FIG. 21B depicts a method for spraying covetic materials into asubstrate, in accordance with one or more of the disclosedimplementations.

FIG. 21C is a schematic depicting a plasma spray process that is usedfor spraying a film, in accordance with one or more of the disclosedimplementations.

FIG. 22A depicts an apparatus for wrapping carbon particles with amolten metal, in accordance with one or more of the disclosedimplementations.

FIG. 22B depicts a method for wrapping carbon particles with a moltenmetal, in accordance with one or more of the disclosed implementations.

FIG. 23A, FIG. 23B, FIG. 23C, and FIG. 23D, depict example depositiontechniques, in accordance with one or more of the disclosedimplementations.

FIG. 24A and FIG. 24B depict conventional deposition techniques forplacing materials onto a substrate, in accordance with one or more ofthe disclosed implementations.

FIG. 25A and FIG. 25B depict example deposition techniques that resultin covalent bonding at the surface of a substrate, in accordance withone or more of the disclosed implementations.

FIG. 26A, FIG. 26B, FIG. 26C, FIG. 26D, and FIG. 26E depict schematicdiagrams that illustrate how covalent bonds are formed between sites inthe square shapes of a face-centered cubic structure of aluminum andsites in the hexagonal shapes that occur in certain crystallographicstructures of carbons.

FIG. 27A depicts an example apparatus for producing covetic material ina powdered form, in accordance with one or more of the disclosedimplementations.

FIG. 27B1 and FIG. 27B2 depict an example fluidized bed apparatus forcooling and handling powdered covetic materials in a fluid, inaccordance with one or more of the disclosed implementations.

FIG. 27C is a schematic depicting a plasma spray process that is usedfor production of a powdered covetic material, in accordance with one ormore of the disclosed implementations.

FIG. 28 depicts method for making components from powdered coveticmaterials using injection molding techniques, according to someimplementations.

FIG. 29 depicts various properties of covetic materials.

DETAILED DESCRIPTION

Aspects of the present disclosure are directed to approaches forcreating covetic materials using spraying techniques, rather than bymixing carbon-based materials into the bulk of a molten metal slurry.Some implementations relate to techniques for reduction of the size ofinterstitial carbon structures down to the nanometer (nm) scale. Theaccompanying figures and discussions herein present exampleenvironments, example systems, and example methods for creating“covetic” materials, understood generally and defined herein to implycomprised of high concentrations (>6% wt) of carbon, integrated intometals (or metal-containing materials) in such a way that the carbondoes not separate out during melting or magnetron sputtering. Theresulting material has many unique and improved properties over the basemetal from which it is produced. The carbon is dispersed through themetal matrix in several ways that contribute to improvements in materialproperties. The carbon is bound into covetic material very strongly,often resisting many standard methods at detecting and characterizingits form. Inclusion of nanoscale carbon raises the melting points andsurface tension. Covetics have higher warm-worked and cold-workedstrengths.

Identification and Significance of Problem and Opportunity

Metal matrix composites may be composed of (at least) a metal or metalalloy (referring to a metal made by combining two or more metallicelements, especially to give greater strength or resistance tocorrosion) matrix, in combination with a higher strength modulusceramic, carbon-based reinforcement, or micro filler in the form ofcontinuous or discontinuous fibers, whiskers, or particles. The size ofthe reinforcement is important as micron-sized reinforcement metals mayexhibit improved strength and stiffness up to acceptable levels overbase alloys. Nevertheless, such improvements may also be accompaniedwith undesirably poor ductility and undesirably low yield strength,machinability, and fracture toughness at threshold loadings due toundesirable agglomeration between particles during processing. To avoidpremature cracking and other shortcomings of metal matrix compositeswith incompatible micron-sized reinforcements, it can essential toreduce the size of a reinforcing phase to nanometer scale. Further,methods are needed such that the reinforcing phase is incorporated intothe metal alloy matrix.

Significant increases in mechanical, thermal, electrical, andtribological (referring to the science and engineering of interactingsurfaces in relative motion) properties have been observed commensuratewith the addition of the aforementioned carbon-based reinforcement.Notably, such properties may change and/or improve as the size of thereinforcement is reduced from a micron scale to a nanoscale (such as<100 nm) due to increased cohesion forces between the matrix and theparticles. The improvement in properties can be attributed to formationof strong interfaces that promote efficient strengthening mechanisms.Enhancements in tensile and yield strength were reported for nanosizedparticles (˜20 nm) versus micron sized particles (˜3.5 μm), althoughwith as much as an order of magnitude less volume loading of thenano-size particles versus the micron-sized particles. Legacy techniquesmay thus fail to provide reinforcement at nanometer scales. Accordingly,there is a current need for the reduction of carbon structures havinginterstitial vacancies contained therein down to the nanometer scale.

Microwave (MW) Plasma Torch Reactor

Using a microwave (MW) plasma torch reactor, pristine 3D few layergraphene (FLG) particles can be continuously nucleated, such asin-flight in an atmospheric-pressure vapor flow stream of acarbon-containing species, such as methane gas, where such nucleationoccurs from an initially synthesized carbon-based or carbon-including“seed” particle. Ornate, highly structured and tunable 3D mesoporouscarbon-based particles composed of multiple layers of FLG (such as 5-15layers) are grown from the carbon-containing species along withconcomitant incorporation of metal elements or metal-based alloys toform at least partially covalently bonded (as well as at least partiallymetallically or ionically bonded) carbon-metal composite, also referredto herein as “covetic”, particle structures. In some implementations,“pristine” graphene (referring to graphene with no defects, or very fewdefects) is provided or generated in the described MW torch reactor isnot oxidized, or contains very little (such as <1%) oxygen content. Byitself, in some implementations, metal (in the resultant coveticmaterials) is held together by metallic bonding and, by itself, carbon(prevalent in graphene or some other organized carbon based 2D or 3Dstructure, such as a matrix or lattice), is held together by (primarily)covalent bonds. The composite carbon-metal structure may includecovalent bonds between the carbon and metal atoms that occur at themetal-carbon interface.

Presently disclosed microwave plasma-based reactor processes provide areaction and processing environment in which gas-solid reactions can becontrolled under non-equilibrium conditions (referring to physicalsystems that are not in thermodynamic equilibrium but can be describedin terms of variables that represent an extrapolation of the variablesused to specify the system in thermodynamic equilibrium; non-equilibriumthermodynamics is concerned with transport processes and with the ratesof chemical reactions, and the incipient melting of metal powders thatcan be independently controlled by ionization potentials and momentumalong with thermal energy). After nucleation in-situ (referring toin-place within the reactor or reaction chamber), exiting solid,substantially solid, or semi-solid carbon-based particles from theplasma torch can be deposited in an additive, layer-by-layer fashiononto a temperature-controlled substrate (such as a drum). The exitingparticles can be sprayed onto and bonded onto or into a specificsubstrate. In some instances, a substrate is not used, rather, groupingsof exiting semi-solid particles form one or more directionallyorganized, free-standing, self-supported structures. Unlike a standardplasma torch where operational flows, power and configuration arelimited, presently disclosed microwave plasma torch includes controlmechanisms (such as flow control, power control, temperature control,etc.) to independently control one or more constituent materialtemperatures and gas-solid reaction chemistries to create unique,ornate, highly-organized, covalently-bound carbon-metal structureshaving a favorably surprising and extremely high degree of homogeneity.

Covetic materials produced by the presently disclosed MW reactor-basedtechniques yield various competitive advantages otherwise not availablein current materials or products. One such advantage relates to aninherent scalability and versatility to formulate unique, physically andchemically stable, versatile metal-carbon composites exhibitingpredictable deformation (referring to stress, strain, elasticity, orsome other ascertainable physical characteristic) in a variety ofconfigurations and/or architectures such as (but not limited to): (1)dense thin film implantations, (2) coatings, (3) thick strips, and (4)powdered particles that can be subjected to subsequent re-melting andcasting and/or for use in forming engineered metal alloy components. Anyof the foregoing dense thin film MW-reactor produced carbon-based metalcomposite implantations and/or coatings, and/or strips, and/or powderedparticles all exhibit enhanced physical, chemical, and electricalproperties as compared with existing parent metal alloy formulations.

OVERVIEW

The disclosure herein describes integration of a low dose nanofillercarbon-based material such as graphene, known for its inherentstructural characteristics such as a high aspect ratio and “2D” planargeometry, with metals. Graphene possesses astonishing favorablemechanical, physical, thermal and electrical properties due to itsin-plane sp² C═C bonding (resulting in 2D planar geometry). Therefore,graphene would serve as an ideal reinforcement for metal matrixcomposites as compared with alternatives such as micro-fillerpolyacrylonitrile (PAN)-based carbon fiber. It should be noted that evenat low graphene nanoplatelet content (loadings), a 3D network is formedwith an anisotropic (referring to an object or substance having aphysical property that has a different value when measured in differentdirections), that result in marked improvements to thermal andelectrical conductivities as well as mechanical features.

A challenge encountered in using carbon nanofillers in metal matrixcomposites includes difficulty with dispersion due to poor wetting(referring to the ability of a liquid to maintain contact with a solidsurface, resulting from intermolecular interactions when the two arebrought together; the degree of wetting, referred to as wettability, isdetermined by a force balance between adhesive and cohesive forces). Theincreased surface area presented by nanofillers causes particles toagglomerate into clusters and twists due to Van der Waals forces betweencarbon atoms. Agglomerates and clustering of nanofillers in metal matrixcomposites can lead to formation of undesirable cracks and pores thatmay ultimately compromise structural integrity of the resultant materialyielding premature failure under high load or performance conditions.

Although a number of processing approaches, such as conventional powdermetallurgy, hot rolling, casting, and additive manufacturing have been(and may currently also be) used to produce metal matrix composites,there are still challenges with uniformly dispersing nanofillers. Damageto nanofiller from applied stress during consolidation, and undesirableor uncontrollable chemical reactions with the matrix at elevatedtemperatures during sintering and casting, are some examples ofchallenges faced during attempts to achieve nanofiller dispersion.

Defect free, the basal plane of graphene exhibits exceptional favorablechemical stability compared to sides and ends of a graphene sheet, whichmay be more prone to interact with metals to form carbides(thermodynamically favored as per the Gibbs free energy). Duringprocessing, however, defects can readily form in the basal plane,leading to carbide formation and adverse effects to compositeproperties. Hence, relatively severe processing conditions such as hightemperatures and pressures, can adversely affect the quality of theinterface between carbon nanofillers and their surrounding metal-basedmatrix. Specifically, high temperatures and pressures can adverselyaffect wetting ability, structural integrity, may unwantedly influencecarbide formation, and may otherwise cause other deleterious interfacereactions.

An alternative process, referred to as covetics (as introduced earlier),has been successfully used to incorporate carbon nanofillers into metalmatrices. In covetic related processes, a network of graphene ‘ribbons’and nanoparticles have been shown to form within a liquid metal by usingan applied electric field that exhibits exceptional stability within themetal matrix, even after re-melting. Correspondingly, the compositestructure conducts heat and electricity more efficiently than the parentmetal.

Uniform Dispersion

Since one of the challenges to incorporating graphene into a metalmatrix is achieving uniform dispersion, covetics processing overcomesthis problem through the concomitant exfoliation and wetting of thegraphene ribbons and/or particles within an applied electric field(either from the carbon electrodes or from the breakdown of carbonadditives). Impurities, such as oxygen and hydrogen, can be managed viaredox reactions at the particle surface, assuming a properly inducedvoltage at the surface, to promote wetting/dispersion. A challenge isone of controlling the structural integrity and uniformity of thegraphene ribbons and/or particles (such as uniformity with respect tosize, defects, etc.), as well as controlling chemical reactivity withthe metal at elevated temperatures, and as well as controllingdistribution of particles in the bulk as well as at the surface of themelt.

Additional Complexities

Although fundamental modes of energy conduction in metals (both thermaland electrical) can be (at least in part) carried out by electrons andis controlled by the degree of crystallinity and impurities for a fillersuch as graphene to enhance thermal conductivity in the metal matrixcomposite (where conduction is via phonons in graphene), there eitherneeds to be some degree of registry and/or coherency (such as anintegrally bound nano scale carbon) with the metal lattice (additionallyor alternatively referred to as a scaffold, matrix, or structure) or aminimum platelet spacing (such as proximity or network) threshold forconduction between platelets (such as the graphene would need to be asingle layer or just a few layers and 10′s of nanometers in length).With respect to strengthening the metal matrix, however, graphene mayneed to be chemically (or in some instances, also physically) bonded tothe matrix for proper load transfer (noting that the length of graphenecan be greater than ˜0.5 μm for maximum load transfer). Aside from solidsolution strengthening, which relies on coherent and/or semi-coherentelastic strains between carbon (graphene) nanofiller and metal lattice,a discrete graphene nanoparticle can serve as a barrier to dislocationpile-up or pinning (such as Hall Petch grain refinement, referring to amethod of strengthening materials by changing their average crystallite(grain) size; it is based on the observation that grain boundaries areinsurmountable borders for dislocations and that the number ofdislocations within a grain have an effect on how stress builds up inthe adjacent grain, which will eventually activate dislocation sourcesand thus enabling deformation in the neighboring grain, too; so, bychanging grain size one can influence the number of dislocations piledup at the grain boundary and yield strength) at grain boundaries, bothof which improve mechanical properties.

Again, because of its 2D nature and high surface area, graphene canorient along regions at grain boundaries in addition to aligning alongslip planes within the metal structure. Irrespective of whether theproperty of interest is chemical, mechanical, thermal or electrical, thegreater the alignment and registry of the nanofiller to the crystalstructure of the surrounding metal matrix (at the atomic level), thegreater the enhancement as well as stability of the property in a metalmatrix composite structure.

Fundamentally, growth of carbon at a metal surface (heterogeneous) orprecipitation out of solution in the melt (homogeneous) is dependent onthe solubility of carbon in the metal (as per the binary phase diagramshown on the right side of FIG. 10 ). The solubility of carbon in puretransition metals (and many pure metals, generally) is very low, such asnear the melting point of the metal, although increases as thetemperature increases to well above the melting point of the metal (suchas up to 2,000° C. and above). The solubility of carbon in nickel, forexample, near the hypereutectic point of around 2.5% is one of thehigher solubilities of carbon in a pure metal. Note that the addition ofinterstitial impurities such as oxygen, boron, or nitrogen, orsubstitutional atoms to a metal, can affect (such as potentiallyincrease) the solubility of carbon. It has been shown that the higherthe solubility of carbon in a metal, or the higher the temperature ofthe molten metal, the thicker the carbon that precipitates at thesurface of the metal as the metal is cooled down and solidified.Important to note is that solubility of carbon is higher near a freesurface, which, in combination with the interfacial energy of theliquid-air interface, favors precipitation of solid carbon at the metalmelt-air interface. Equipment and techniques for operating the equipmentto overcome the problems attendant to this phenomenon are addressed aspertains to the figures and corresponding discussions.

Definitions and Use of Figures

Some of the terms used in this description are defined below for easyreference. The presented terms and their respective definitions are notrigidly restricted to these definitions—a term may be further defined bythe term's use within this disclosure. The term “exemplary” is usedherein to mean serving as an example, instance, or illustration. Anyaspect or design described herein as “exemplary” is not necessarily tobe construed as preferred or advantageous over other aspects or designs.Rather, use of the word exemplary is intended to present concepts in aconcrete fashion. As used in this application and the appended claims,the term “or” is intended to mean an inclusive “or” rather than anexclusive “or”. That is, unless specified otherwise, or is clear fromthe context, “X employs A or B” is intended to mean any of the naturalinclusive permutations. That is, if X employs A, X employs B, or Xemploys both A and B, then “X employs A or B” is satisfied under any ofthe foregoing instances. As used herein, at least one of A or B means atleast one of A, or at least one of B, or at least one of both A and B.In other words, this phrase is disjunctive. The articles “a” and “an” asused in this application and the appended claims should generally beconstrued to mean “one or more” unless specified otherwise or is clearfrom the context to be directed to a singular form.

Various implementations are described herein with reference to thefigures. It should be noted that the figures are not necessarily drawnto scale, and that elements of similar structures or functions aresometimes represented by like reference characters throughout thefigures. It should also be noted that the figures are only intended tofacilitate the description of the disclosed implementations—they are notrepresentative of an exhaustive treatment of all possibleimplementations, and they are not intended to impute any limitation asto the scope of the claims. In addition, an illustrated implementationneed not portray all aspects or advantages of usage in any particularenvironment.

An aspect or an advantage described in conjunction with a particularimplementation is not necessarily limited to that implementation and canbe practiced in any other implementations even if not so illustrated.References throughout this specification to “some implementations” or“other implementations” refer to a particular feature, structure,material or characteristic described in connection with theimplementations as being included in at least one implementation. Thus,the appearance of the phrases “in some implementations” or “in otherimplementations” in various places throughout this specification are notnecessarily referring to the same implementation or implementations. Thedisclosed implementations are not intended to be limiting of the claims.

DESCRIPTIONS OF EXAMPLE IMPLEMENTATIONS

FIG. 1A is a comparison chart 1A00 showing two different coveticmaterial formation techniques 102 and example materials that result fromthe application of each, respectively.

In the case of conventional metal melt methods 103 to produce coveticmaterials, solid carbon is added to a metal melt. This conventionalmetal melt technique is governed by the kinetics of carbide formationand interdiffusion across a solid-liquid (such as carbon-metal)interface under an applied current, which provides additional energy toovercome stacking fault energy between carbon atoms and metal atoms. Assuch, conventional metal melt techniques for forming covetic processingdo not significantly differ from other composite processing methods,such as powder metallurgy and/or hot rolling, which composite processesinvolve consolidation of a second phase particle into a metal matrix.These conventional composite processing methods face many challengeswith dispersion and/or distribution, reactivity, and variability inmaterial properties. Furthermore, conventional covetic processing relieson batch processing, and often yields inconsistent conversion yields aswell as wide variations in resultant properties.

As depicted by agglomeration image 105, when using conventional metalmelt methods 103, the resultant material suffers from extremeagglomeration of carbon, which in turn: (1) limits the role of carbon toreinforce the lattice; and, (2) limits the tunability of the surfacemorphology for surface functionalization. For comparison, when usingpresently disclosed techniques, the resultant material exhibits nearlyuniform homogeneity (such as no agglomerates), which homogeneity resultsfrom uniform dispersion of carbon into the lattice. This is shown inhomogeneity image 106.

Covetic materials such as are depicted in homogeneity image 106 can becharacterized by many desirable material properties 108 such asuniformity, high carbon loading, low carbon content at surfaces, etc.These are highly desirable material properties that are not exhibited bymaterials formed using conventional metal melt methods 103. Therefore,what is sought after are improved approaches that overcome shortcomingsof the conventional metal melt methods 103.

One such improved approach involves plasma spray torch methods 104.Application of plasma spray torch methods result in a consistent yieldof covetic materials, thus overcoming the yield shortcomings ofconventional metal melt methods. Furthermore, application of plasmaspray torch methods results in covetic materials that possess theaforementioned improved mechanical, improved thermal, and improvedelectrical properties, thus overcoming resultant material shortcomingsof conventional metal melt methods.

Improved Approaches

As shown, the plasma spray torch methods 104 can be configured to useinput materials as introduced (referring to provision of acarbon-containing feedstock species in gaseous form, such as methane,and energizing it via application of MW energy directed through themethane gas, etc.). However, by dissociating carbon-containing gas (suchas methane or other hydrocarbon sources) at elevated temperatures, aself-limited monolayer of carbon—and in particular, pristinegraphene—can be grown onto and/or into a metal (such as copper, gold,zinc, tin, and lead) lattice. The number of monolayers is dependent atleast in part on the solubility of carbon in the metal. Growth kinetics,binding, and the final structure of graphene films onto a metalsubstrate is dependent on the valence electrons and the symmetry (closepacked planes) of the metal. Similarly, metals can be grown on carbon,preferentially nucleating and growing at defect sites of the carbon orat selective oxygen- or hydrogen-terminated sites as well. Alternatingstacks of single layer carbon and metal can then be fabricated torealize the enhanced properties of a graphene-reinforced metal compositestructure.

Using a microwave plasma reactor, pristine 3D few-layer grapheneparticles can be continuously nucleated and grown from a hydrocarbon gassource. In addition, selective elements can be incorporated into the 3Dgraphene particle scaffold by adding them to the plasma gas stream. Themicrowave plasma reactor process provides a unique reaction environmentin which gas-solid reactions can be controlled under non-equilibriumconditions (such as chemical reactions can be independently controlledby ionization potentials and momentum along with thermal energy).Reactants can be inserted as solids, liquids or gases into a plasmareactor zone to independently control nucleation and growth kinetics ofunique non-equilibrium structures (such as graphene on metal and metalon graphene).

For example, to create integrated graphene-metal composites at thenanometer scale, fine nanometer-scale metal particles can be introducedinto a microwave plasma torch along with a hydrocarbon gas such asmethane. Methane dissociates into hydrogen and carbon (such as using theideal energy of the microwave plasma to form C and C₂) which can thennucleate and grow ordered graphene onto the semi-molten surface of themetal particle. Non-equilibrium energy conditions can be created bytuning process conditions to independently control the temperature ofthe metal with respect to carbon reactivity and delivery to the metalsurface. Ionized hydrogen (or other ions) at controlled low energies canbe used to impinge/sputter the surface of the growing graphene-metalsurface without damaging the structure of the graphene-metalcomposition. This then promotes further growth of alternatinggraphene-metal layers. In addition, depending on residence time and theenergetics within the plasma reaction zone, metal-graphene structurescan be created with specific properties that are retained when themetal-graphene structures are rapidly cooled upon being sprayed onto asubstrate at a controlled temperature. The formation of themetal-graphene structures at controlled energies within the plasma aswell as control of the temperature of the substrate provides independentcontrol of energetic conditions throughout the entire evolution of thesecovetic materials.

Graphene can be applied (and/or deposited) onto metal ormetal-containing layers of material via “sputtering” (referring to aphenomenon in which microscopic particles of a solid material areejected from its surface, after the material is itself bombarded byenergetic particles of a plasma or gas; the fact that sputtering can bemade to act on extremely fine layers of material is often exploited inscience and industry—there, it is used to perform precise etching, carryout analytical techniques, and deposit thin film layers in themanufacture of optical coatings, semiconductor devices andnanotechnology products, etc.). Such sputtering, as so described, can becontrolled by controlling residence times and energetics within theplasma reaction zone to promote growth of alternating graphene-metallayers when employed with the presently discussed MW plasma reactors.These alternating graphene-metal layers are organized in coherent planesof atoms that are in a regular (such as crystallographic) configuration.This crystallographic configuration is retained when the graphene-metallayers are quick-quenched (in the materials science field, quenching, orquick/rapid quenching, refers to the controlled rapid cooling of aworkpiece in water, oil or air to obtain certain material properties; atype of heat treating, quenching prevents or controls undesiredlow-temperature processes, such as phase transformations, from occurringby reducing the window of time during which these undesired reactionsare both thermodynamically favorable and kinetically accessible; forinstance, quenching can reduce the crystal grain size of both metallicand plastic materials, increasing their hardness) onto a coolersubstrate. Quick quenching, as so described, serves to essentially‘freeze’ (referring to retention in a substantially solid state ratherthan solely on the traditional definition of change in phase from aliquid to a solid) graphene to metal in a desired crystallographicconfiguration formed within the plasma reactor. The homogeneity withinand at the surface of the resultant material is extremely uniform. Thisextremely uniform homogeneity can be used to distinguish from materialsthat had been formed using metal melt methods 104. This is because themetal melt methods 104 cannot control ion energies independently fromthermal energies. More specifically, because the metal melt methods 104cannot achieve the desired higher ion energies independently fromthermal energies, temperatures in the metal melt reaction chamber can betoo high for graphene-metal layers to become organized in coherentplanes of atoms that are in the desired crystallographic configuration.

Therefore, when using metal melt methods 104, the desiredcrystallographic configuration of the graphene-metal never occurs, andthus desired crystallographic configuration cannot be retained when thegraphene-metal layers are quenched onto a cooler substrate. Instead,when using metal melt methods 104, undesired carbon precipitation occurs(such as carbon precipitates out of the melt), which in turn leads tounwanted agglomeration, which in turn leads to non-uniformity in theresultant. This non-uniformity in the resultant can lead to less thanideal chemical and/or physical (mechanical) characteristics in theresultant materials, including but not limited to premature mechanicalfailure.

FIG. 1B presents a high-resolution transmission electron microscopyimage 114 and a high-resolution energy dispersive spectroscopy x-rayimage 116. Also shown here for convenience is the homogeneity image 106of FIG. 1A.

As depicted by this example set of images, the carbon is distributeduniformly throughout the metal lattice. This is emphasized in thehigh-resolution transmission electron microscopy image 114. Moreover,the extremely high carbon loading in the metal lattice is clearly shownby the high-resolution energy dispersive spectroscopy x-ray image 116.In this example, the carbon loading forms approximately 60% of theoverall copper-carbon lattice. This is shown in the high-resolutionenergy dispersive spectroscopy x-ray image 116. In this particularimage, the darker areas are carbon and the lighter areas (appearing asdots) are copper.

As can be seen the images, and in particular, as can be seen from thepattern of the high-resolution energy dispersive spectroscopy x-rayimage 116, the carbon and the parent metal (such as in this casecopper), are uniformly dispersed. This uniform lattice-level dispersionis present at the surface, as shown, moreover, this uniformlattice-level dispersion is also present deep into the parent metal.Additional images of covetic materials are given in FIG. 20A1, FIG. 20A2and FIG. 20B, which figures follow after discussion of (1) materialsevolution processes, (2) a plasma spray torch apparatus and (3) variousconfigurations of plasma spray torches.

In one use scenario, the covetic materials of FIG. 1B can bemanufactured using a tunable microwave plasma torch that producesintegrated graphene-metal composite films at high rates and volumes. Oneparticular manufacturing process during which graphene is grown ontosmall molten metal particles is now briefly discussed.

FIG. 2 depicts a manufacturing process 200 for growing graphene ontosmall molten particles. As an option, one or more variations ofmanufacturing process 200 or any aspect thereof may be implemented inthe context of the architecture and functionality of the implementationsdescribed herein. The manufacturing process 200 or any aspect thereofmay be implemented in any environment.

One possible method is to use a “non-equilibrium energy” microwaveplasma torch to provide non-equilibrium control over the temperature ofthe metal independently from carbon creation. This plasma torch energyis then directed to the molten and/or semi-molten metal particlessurfaces. This technique allows time for growth to occur on the melt.Growth on the melt (or semi-melt or core shell materials) created withinthe torch will flow out through the main plasma plume to the surface ofthe metal to be grown upon, and then is quickly quenched. This techniqueprovides a means to grow thick films which, upon layering, could begrown into a homogeneous thick ingot and/or grown into or onto componentparts to be post machined or remelted into applications.

Additionally, FIG. 2 is being presented to illustrate the effects thatindependent control of constituent material temperatures and gas-solidreaction chemistries when growing graphene onto small molten particles.FIG. 2 shows the evolution through several processes of coveticmaterials manufacturing; and, presents processes used in the formationof plasma torch-based covetic materials.

As shown, semi-solid particles exiting from the plasma torch can bedeposited in an additive, layer-by-layer fashion onto atemperature-controlled substrate. Unlike a standard plasma torch whereoperational flows, as well as control of power and other configurationsare limited, the discussed microwave plasma torch can be operated toindependently control constituent material temperatures as well asgas-solid reaction chemistries.

As can be seen from the disclosure above, microwave plasma sources canresult in (for example): (1) higher plasma densities; (2) ion energieswith a narrower ion energy distribution; and, (3) improved coatingproperties. This is due, at least in part, to the improved powercoupling and (electromagnetic energy) absorption at 2.45 GHz. Pressuredependent, typical electron temperatures are of the order of 1 eV to 15eV yielding plasma densities of >10¹¹ cm⁻³. Such low electrontemperatures are also advantageous not only in terms of controlling theplasma chemistry, but also in terms of limiting the ion energy with ionenergies for Argon-based coaxial microwave plasmas that typically are inthe range of 5 eV to 80 eV. As a consequence of the narrow plasma sheathformed using these high-density plasmas, collisional broadening of theion energy distribution is prevented, thus resulting in a sharp ionenergy distribution that supports fine control of certain filmdeposition processes. Additionally, through the usage of pulsed powerinto a microwave plasma, non-equilibrium energies can be formed andcontrolled. During application of microwave energy, power is deliveredthroughout a volume where plasma is to be formed, thus energy isaccumulated in a stepwise collisional energy regime.

The foregoing discussion of FIG. 2 includes techniques for applicationof microwave energy power, which technique is disclosed in furtherdetail as follows.

FIG. 3 depicts a plasma energy state chart 300 showing how a pulsedmicrowave energy source is used for growing graphene onto small moltenparticles.

Microwave plasma sources have the potential to achieve higher plasmadensities, ion energies with a narrower ion energy distribution, andimproved coating properties as a consequence of improved power couplingand absorption at 2.45 GHz. Pressure-dependent typical electrontemperatures are of the order of 1 eV to 15 eV yielding plasma densitiesof >10¹¹ cm⁻³. Such low electron temperatures are also advantageous notonly in terms of controlling the plasma chemistry, but also in terms oflimiting the ion energy with ion energies for Argon-based coaxialmicrowave plasmas that typically are in the range of 5 eV to 80 eV. As aconsequence of the narrow plasma sheath formed using these high-densityplasmas, collisional broadening of the ion energy distribution isprevented resulting in a sharp ion energy distribution, which isnecessary for fine control of some film deposition processes.Additionally, through the use of pulsed power being delivered into amicrowave reactor, plasma non-equilibrium energies can be formed andcontrolled. During application of microwave energy, power is deliveredthru a volume where plasma is to be formed, thus energy is accumulatedin a stepwise collisional energy regime.

Once the initial plasma forms in the vast majority of the volume, thedelivery antennae where energy is at a maximum continues to increase ina highly localized fashion. Plasma density nearby decreases slightlyuntil the plasma constricts. Further details regarding generalapproaches to making and using pulsed microwave energy sources aredescribed in U.S. Pat. No. 10,332,726, issued Jun. 25, 2019, which ishereby incorporated by reference in its entirety.

FIG. 3 shows that the initial energy of the plasma is much higher in thenon-equilibrium state until it constricts to a much lower stabletemperature. More specifically, the plasma energy state chart depicts atransition from an initial high energy non-equilibrium state to a lowerenergy stable equilibrium state. Once the initial plasma forms, thedelivery antennae, where energy is at a maximum, will continue toincrease in a highly localized fashion until the plasma constricts andis lost in the remaining parts of the chamber due to energy shielding.

The pulsed microwave energy source can be controlled so as to optimizeelectron temperatures for growing graphene onto small molten particles.This is especially effective in the case where pressures are >>20 Torr.To ensure that plasma chemistry dissociation is homogeneous, and thatcoating of materials is homogeneous as well, the environments of thechamber must be controlled.

As is shown in FIG. 3 , the energy profile indicates that the initialenergy is high and, after a time, constricts to a lower level where itstays until the power is removed. The plasma extinguishes and, afterrestarting, follows the energy cycle again. By reducing the time betweenthe initial plasma ignition and where it stabilizes, the plasma remainsmainly in the bulk of the system where a more homogeneous dissociationof materials can occur. The reduction of the time between the initialplasma ignition and the time when it stabilizes can be accomplished bycontrolling the frequency and duty cycle of pulsing.

One technique for controlling electron temperatures in a pulsedmicrowave reactor is shown and described as pertains to FIG. 4 .

FIG. 4 depicts an electron temperature control technique 400 that isused for growing graphene onto small molten particles. As an option, oneor more variations of electron temperature control technique 400 or anyaspect thereof may be implemented in the context of the architecture andfunctionality of the implementations described herein. The electrontemperature control technique 400 or any aspect thereof may beimplemented in any environment.

FIG. 4 illustrates aspects pertaining to growing a few layers ofgraphene onto molten nanoscale-sized particles rather than mixingcarbons into the bulk of a molten slurry. Specifically, the figure isbeing presented with respect to its contribution to controlling plasmatemperature through control of microwave pulsing frequency.

Plasma Temperature Control via Control of Pulsing Frequency

As depicted in the foregoing FIG. 3 , the energy profile indicates thatthe initial energy is high and, after a time, constricts to a lowerlevel where it stays until the power is removed. The plasma extinguishesand, after restarting, follows the energy cycle again. By reducing thetime between the initial plasma ignition and stabilization, the plasmaremains mainly in the bulk of the system where a more homogeneousdissociation of materials can occur.

As shown in FIG. 4 , the effect depends substantially on the timing ofthe on/off cycle of the microwave energy source. By controlling thefrequency of pulsing, optimal chemical dissociation and uniform coatingscan be created. Furthermore, by setting the pulsing frequency, theaverage temperature of the plasma can be controlled as well.

Plasma Temperature Control in a Microwave Plasma Torch

The herein-discussed integrated microwave plasma torch is used foraddressing the formation of integrated, second phase, carbon-metalcomposite structures with enhanced mechanical, thermal and electricalproperties over existing metal alloys and conventional compositeprocessing methods. Furthermore, the microwave plasma torch can be usedto form carbon-metal composite coatings and particles directly onto highvalue asset components. Still further, the aforementioned methods andequipment meet many clean energy goals pertaining to improved electricaldistribution and efficient transformer and heat exchanger performance.

Microwave Plasma Torch Practical Applications

Using the integrated microwave plasma torch technology, materials can beeconomically (such as cost effectively) deposited and/or formed at fastrates and can be applied and in a variety of different configurations.Benefactors of this technology include various energy productionindustries—especially as pertains to transmission andstorage—transportation industries, military equipment industries, aswell as many other manufacturing industries. As one specific practicalapplication example, metallic surfaces of an aircraft can be treated bya plasma spray to create covetic material at the metal-air interface.The metallic surfaces thus become impervious to corrosion. Additionally,the carbon atoms near the surface allows for other materials to bechemically bonded to the carbon atoms and/or adhered to the surfaces.The aforementioned other materials that can be chemically bonded to thecarbon atoms might be selected on the basis of requirements that arisein various practical applications.

As another specific practical application example, metallic surfaces ofan airborne vehicle (such as an airplane, helicopter, drone, projectile,missile, etc.) can be treated by a plasma spray to create a coveticmaterial coating that acts as an infrared obscurant (such as a detectioncountermeasure).

FIG. 5 illustrates a dual plasma torch apparatus 500 that is used forgrowing graphene onto small molten particles. As an option, one or morevariations of dual plasma torch apparatus 500 or any aspect thereof maybe implemented in the context of the architecture and functionality ofthe implementations described herein. The dual plasma torch apparatus500 or any aspect thereof may be implemented in any environment.

The shown equipment setup uses: (1) a metal plasma spray torch to supplymolten metals to the surface of the heated substrate (Al, Cu, Ag, etc.),and (2) a microwave plasma torch to deliver ionized carbon and plasmaradicals to the molten surface so as to cause the covetics growth ontomolten metals.

The system is inserted into an inert gas environment or into anatmospherically controlled chamber to provide better control ofmaterials oxidation. In one implementation, the setup and operation ofthe torch of FIG. 5 is shown in Table 1, the details of which arediscussed infra.

TABLE 1 Step Setup & Operation Description 1 Identify and selectreactant materials 2 Integrate a standard, non-microwave plasma spraytorch and a microwave plasma torch into a dual-plasma torch 3 Defineplasma torch processing parameters 4 Operate the dual plasma torch toproduce graphene growth on a semi-molten particle surface

Step D1: Reactant Material Identification and Selection

Any number of metals can be plasma-sprayed concurrently along withmetastable carbon species to form a nano-carbon-metal compositestructure. Different metals with high electrical and thermalconductivity can be used when forming 2D graphene at concentrationsabove the thermodynamic solubility limit. In some cases, two differentmetals are selected, each having different carbon solubility limitsand/or different melting points and/or different densities and/ordifferent crystal structures.

Step D2: Selection, Modification and Validation of Microwave and‘Standard’ Plasma Spray Torch(es)

The apparatus of FIG. 5 can be (in certain implementations)substantially composed of a ‘standard’, off-the-shelf, plasma spray anda microwave plasma torch. Having two torches allows for two differentprocessing steps, namely: (1) incipient melting of the metal, and (2)nucleation/growth of graphene platelets from a hydrocarbon source. Eachone of the two torches can be controlled independently from each other.

As shown in FIG. 5 , the two torches are collocated for concurrent orsequential operation. Specifically, the microwave plasma with its lowelectron temperature and high electron density can be used to optimizegraphene formation (including nucleation rate at the carbonsupersaturation threshold) whereas the standard plasma spray torch canbe used to heat metal powder/particles to a molten or semi-molten stateand then accelerate the particles (along with nucleated ionizedcarbon/graphene) towards the substrate. The two independent flow streamscan be coordinated so as to accomplish fine-scale graphene growth on asemi-molten particle surface. In some cases, the dual torchconfiguration comprises a means to maintain an inert atmosphere (such ascover gas) at or near the exit stream of the torches and in and aroundthe impingement region at the surface of the substrate. This is becausecontaminants from the surrounding air (such as oxygen, nitrogen andmoisture) can affect bonding between the carbon and metal atoms.Therefore, in certain implementations, the dual torch system isconfigured to be inserted into a fully controlled inert gas environment(such as a chamber) so as to provide effective control of materialoxidation.

Step D3: Rationale and Definition of Plasma Processing Parameters

Reactants (such as hydrocarbons) and inert gases and flows are selectedto ensure the stability of plasma and to ensure control of nucleationand growth processes within the plasma (such as supersaturationthresholds for a given gas mixture and flow rate). Acceleration ratesand temperatures of the metastable carbon are controlled duringexcursion from the plasma to the substrate. Correspondingly, processconditions for the standard plasma spray torch are set so as to create aconsolidated thin film onto which carbon can impinge and react. Surfacetemperature and local gas phase environments are controlled so as topromote interaction and growth of the metastable carbon phase.

Step D4: Operate the Dual (Metal and Microwave) Plasma Torch

Various parameters of processing windows of both the metal and microwaveplasma torch are configured to be controlled independently or, in someimplementations, in conjunction with each other. Before, during andafter operation of one or more of the metal and microwave plasma torches(referred to herein as “the dual plasma torch”), processing windows forintegrated carbon-metal formation are characterized. Furthermore, one ormore parameters or combinations of parameters are selected, depositionof carbon-metal is observed, and using any known-in-the-art techniques,the as-deposited samples can be characterized with respect to variousdifferentiators, including (but not limited to): morphology (such asusing a scanning electron microscope (SEM)), structure (such as viax-ray diffraction (XRD) and via Raman spectroscopy), and/or physical andchemical composition.

FIG. 6 illustrates a pulsed microwave plasma spray torch apparatus 600that can be tuned for growing graphene onto small molten particles. Asan example, one or more variations of pulsed microwave plasma spraytorch apparatus 600 (or any aspect thereof) may be implemented in thecontext of the architecture and functionality of the implementationsdescribed herein. The pulsed microwave plasma spray torch apparatus 600(or any aspect thereof) may be implemented in any environment.

In this configuration, transverse electric (TE) microwave energy powermeans can be coupled onto (or, in some implementations, also penetratesubstantially within) a central dielectric tube to propagate microwaveenergy into and throughout the central dielectric tube. Gas suppliedinto the center region (in this example) can be a hydrocarbon gas suchas methane that absorbs the microwave radiation. Metal powder issupplied (as carried by a substantially inert carrier gas) to be heatedwithin the body (or primary chamber) of the pulsed microwave plasmaspray torch apparatus 600 from the combination of the plasma-derived andapplied thermal energy. Upon exposure to such energy, metal powder meltsupon reaching a melting temperature to produce a viscous flowable liquidmaterial, or droplets (potentially containing semi-solid materials), orany other conceivable dispersion (largely dependent on attendant meltconditions).

As hydrocarbon gas decomposes into its constituent element species,carbon radicals nucleate on exposed surfaces of the melted metaldroplets. The combination of energy tuning settings of the microwave,and thermal plume temperature settings can allow for differenttemperatures between the melt temperature and the plasmadecomposition/ionization temperature in a central region of the pulsedmicrowave plasma spray torch apparatus 600. Non-equilibrium conditionswithin the central chamber or region of the plasma spray torch apparatus(referring to temperature, pressure, etc.) can allow (or otherwisefacilitate) internal lattice placement (referring to the positioning ofa synthesized lattice structure of carbon materials with that of anyinput metal(s) such that individual carbon and metal atoms can be atleast partially aligned) of the graphene/carbon, whereas the quickquenching creates conditions conducive to covetic materials growth.Diagrams showing internal lattices where the lattice of the carbon andthe lattice of a metal are oriented such that carbon and metal atoms areat least partially aligned are presented in FIG. 8A-B, FIG. 12 , FIG.26C, and FIG. 26D and in corresponding written description, infra.

The single integrated microwave plasma torch of FIG. 6 can be set up andoperated as depicted in the following Table 2, the details of which aredescribed infra.

TABLE 2 Step Setup/Operation Description 1 Deploy a single integratedmicrowave plasma torch 2 Operate the single integrated microwave plasmatorch for the formation of graphene-loaded metal composite alloys 3Characterize the resultants

Step S1: Deploy a Single Integrated Microwave Plasma Torch

FIG. 6 depicts a single integrated microwave plasma torch. The torch hasthe capability to process solid, liquid and vapor reactant feedstockspecies using (for example) a small inert gas or differentially pumpedvacuum for controlling gas flow. The torch can be deployed in anyenvironment (referring to laboratories, research set-ups, or large-scaleindustrial concerns, etc.).

Step S2: Operate the Single Integrated Microwave Plasma Torch forFormation of Graphene Loaded Metal Composite (“Covetic”) Alloys

Microwave energy is delivered in a collinear waveguide configurationalong with a centralized gas feed system for efficient microwave energyabsorption. The microwave energy source is used to heat the metal to asemi-molten state. As the CH₄ (or other hydrocarbon source) decomposes(into its constituent species) within an exhaust plume that is directedinto a surface wave plasma gas dissociation tube, carbon radicals cannucleate (such as in an organized layer-by-layer manner) on the surfaceof the metal droplets via being energized by plasma radicals (directedonto the metal droplets). The energy tuning of the microwave thermalplume temperature and plasma allows for independent control oftemperatures between the melt and the plasma decomposition/ionizationthat occurs within the central region of the pulsed microwave plasmaspray torch apparatus 600.

Process conditions are measured and optimized. Desired processconditions are controlled by or for the integrated microwave plasmatorch to directly form graphene-loaded metal composite material within asingle or multi-stage plasma reaction torch. The plasma torch can bemodulated within different regions of the surface wave plasma to enhanceresonance (modulation) times and to optimize formation of targetedmetal-carbon structures.

In addition to the shown process gas port (such as for introduction of ahydrocarbon process gas 605) at the depicted location, additional ports604 can be provided at different locations. Such additional ports can beused to control how the process gas is introduced into the microwavefield, and to introduce other process gasses. As examples, a process gasmight be SiH₄ or NH₃. In some implementations, more than one input portfor gas or more than one input port for particles (such as one forcarbon and one for metal) may be included, where the location of theinput ports can be positioned in different zones of the plasma torch.

The foregoing setup and conditions, as well as other conditions areoptimized to result in conditions at the substrate surface that enableimpinging particles to be consolidated into a film. The as-depositedfilms are analyzed and characterized according to methods outlined inStep S3 below.

Step S3: Validate/Characterize the Graphene (Secondary Phase) MetalProperties

Characterization of the as-deposited integrated carbon-metal compositestructures are accomplished using several techniques. For example, x-rayphotoelectron spectroscopy (XPS) and/or SEM-EDS can be used to determinechemical composition, binding energies (nanoscale carbon detection) anddistribution. Also, energy-dispersive x-ray spectroscopy (EDS) and/orSEM, and/or Raman spectroscopy, and/or XRD can be used for determiningmorphology and/or for measuring grain size and structural aspects.Electrical and thermal properties as well as the tensile strength andmodulus of the composite material can be evaluated using any knowntechniques.

Results

The foregoing techniques use a microwave plasma torch to continuouslyfabricate metal matrix composites. The processing entails materialnucleation and formation of a growth zone within the plasma followed byan acceleration and impaction zone for consolidation of the materialsonto a substrate. Each zone provides for unique control of dissimilarmaterials synthesis/formulation and integration; namely, selective andunique formulation of alloy particles within the plasma, which then,through control of momentum (primarily kinetic) and thermal energeticsduring impact onto a substrate, enable a unique additive process forcontrolling consolidation parameters such as porosity, defect density,residual stress, chemical and thermal gradients, phase transformations,and anisotropy.

Various materials are selected for use across a wide range of growthdynamics within the plasma operation environment. In particular,different hydrocarbon gas sources with specific ratios of carbon tooxygen and hydrogen, and solid metal (or metal alloy) particle sourceswith different carbon solubilities, melting points, and crystalstructures can be processed through the pulsed energy plasma torchprocessing system. As such, specific plasma processing parameters can beidentified for concomitant incipient surface melting of the particlealong with nucleation/growth and incorporation of 2D graphene andre-sputtered metal at the metal surface.

Upon incorporation of graphene into the metal from the microwave plasmatorch, as-deposited materials/films are characterized with respect to“covetic-like” properties. As examples, these covetic-like propertiescan be characterized as (for example): (1) chemical composition (such asto detect impurities and to detect forms of carbon); (2) distributionsof carbon (such as interstitial—referring to positions of carbon atomsor species within a metal matrix or lattice, intragranular andintergranular); (3) electrical conductivity; and, (4) mechanicalstrength of the materials. The characterizations may include comparisonsbetween graphene loaded versus un-alloyed parent metals. Further, andstrictly as examples, using the microwave plasma torch, the as-depositedmaterials may exhibit a ratio of carbon to metal throughout the range(inclusive) of about 3% to 90%. In some situations, the ratio of carbonto metal is throughout the range (inclusive) of about 10% to about 40%.In some situations, the ratio of carbon to metal is throughout the range(inclusive) of about 40% to about 80%. In some situations, the ratio ofcarbon to metal is throughout the range (inclusive) of about 80% toabout 90%. In some situations, the ratio of carbon to metal (inclusive)is greater than 90%. The carbon to metal ratio can be affected (orfurther affected) by parameters or specifications (such as temperatures,thicknesses, homogeneity, etc.) that define the coating process.

FIG. 7 is a diagram 700 depicting a coating process. The figure refersto a metallic substrate, which substrate is subjected to plasma torchspraying of covetic materials, which in turn results in synthesizedcomplex carbon coatings. The metallic substrate might comprise any oneor more of copper, aluminum, or other bulk metallic materials. Thecovetic materials might comprise one or more of carbons, graphene,Nano-onions, carbon nanotubes (CNTs), carbide implanted materials, etc.

The plasma torch spraying serves to coat the input materials withdeposited materials, and can be operated using pulsed energy. As shown,the deposited (such as by layer-on-layer sputtering) materials may beany one or more of carbon, metals (such as Al, Cu, Ti, Ta, etc.), and/oroxides or nitrides.

Several advantages emerge from use of the foregoing torches. Chieflyamong them are the advantages of scalability and versatility ofprocesses to formulate unique stable metal-carbon composites in avariety of configurations/architectures. Theseconfigurations/architectures range from fully dense thin film coatingsto thick strips or particles for subsequent re-melting andcasting/forming into engineered metal alloy components. Each of thesespecies throughout the aforementioned range exhibit unexpectedlyfavorable (and desirable) enhanced mechanical, thermal and electricalproperties when compared to existing parent metal alloy formulations.Additionally, the tunability of the concentration and distribution ofcovalently-bound 2D graphene in a metal alloy matrix above thethermodynamic solubility threshold, and the layer-by layer formation ina non-equilibrium plasma environment, enables a new class of compositematerials that can be engineered to correspond to a specific applicationand/or to correspond to specific property requirements. Moreover, thiscan be done at a significantly reduced cost as compared with othertechniques.

The enhanced mechanical, thermal and electrical properties can apply toa large number of applications that use copper and aluminum alloys. Asexamples, such applications include (but are not limited to): wireconductors and high voltage power transmission cables, microelectronicthermal management and heat exchangers, and numerous applications thatuse thin film electrical conductors such as batteries, fuel cells, andphotovoltaics. In particular, the combination of the microwave plasmatorch process and enabling carbon-metal alloy production providessignificant energy savings in manufacturing as well as increased thermalefficiency and reduced electrical losses in end-application performance.

The foregoing plasma spray techniques depict merely one genre of methodsfor making covetic materials. Another genre involves spraying carbonparticles onto small molten metal particles. Such a genre and variousspecies of that genre are shown and discussed as pertains to FIGS. 8A-B,FIG. 9 , FIG. 10 , FIG. 11 , FIG. 12 , FIG. 13 , and FIG. 14 ., as wellas in the discussions of the figures herein.

FIGS. 8A-B are schematics depicting a plasma spray process 800 that isused for spraying carbon particles onto small molten particles. As anoption, one or more variations of the plasma spray process 800 (or anyaspect thereof) may be implemented in the context of the architectureand functionality of the implementations described herein. The plasmaspray process 800 or any aspect thereof may be implemented in anyenvironment.

The shown plasma spraying techniques are used in various coatingprocesses wherein heated materials are sprayed onto a surface. Thefeedstock (such as the coating precursor) is heated by electrical means(such as plasma or arc) and/or chemical means (such as via a combustionflame). Use of such plasma spraying techniques can provide coatingshaving a thickness in the range of about 20 μm to about 3 mm, dependingon the process and feedstock. The coating can be applied over a largearea and at a high deposition rate. Using the foregoing techniques, thedeposition rate is much higher than can be achieved by conventionalcoating processes such as electroplating or physical and chemical vapordeposition.

In addition (or in alternative) to the example materials above, thetypes of coating materials available for plasma spraying include metals,alloys, ceramics, plastics and composites. They are fed into the spraytorch in powder form or in wire form, then heated to a molten orsemi-molten state and accelerated towards substrates in the form ofmicrometer-size particles. Combustion or electrical arc discharge can beused as the source of energy for plasma spraying. Resultant coatings aremade by the accumulation of numerous layers of sprayed particles. Inmany applications, the surface of the substrate does not heat upsignificantly, thus facilitating coating of many substances, includingmost flammable substances.

FIG. 9 is a scanning electron microscope image 900 showing the effect ofspraying carbon particles (such as with particles sizes from 20 nm to 40microns) onto small molten metal particles. The carbon particles sprayedonto small molten metal particles can be used in various specializedapplications. For example, a plasma aluminum-graphite composite can bespecially designed to provide coatings for turbine engines. Alternativesinclude use of aluminum and titanium alloys. The rate of growth of thisplasma spray coating material is parabolic. The plasma spray coatingmaterial precipitates over short periods of time, which precipitation islargely independent of temperature. For preparation of the materialsurface, certain processes include preheating of the materials. In someimplementations, blasting by grit is performed as well for preparationof the material surface. In some implementations, some portion of theparticles that are sprayed onto the surface are still hot enough to formcovetic bonds at the surface of the substrate. In other cases, smallmolten particles are at a temperature to form metal-to-metal bonds.

Use of the herein-disclosed microwave plasma torch techniques enablesthe creation of improved materials as compared to use of conventionaltorches. Specifically, power control limitations and other configurationconstraints inherent to conventional plasma torches limit the ability ofa conventional plasma torch to independently control input materials andother conditions needed to produce carbons that are effective in thecreation of covetic materials that exhibit sufficiently high quality andhomogeneity.

FIG. 10 shows a chart depicting a graphene growth temperature profile1000 and a binary phase diagram. As an option, one or more variations ofgraphene growth temperature profile 1000 or any aspect thereof may beimplemented in the context of the architecture and functionality of theimplementations described herein. The graphene growth temperatureprofile 1000 or any aspect thereof may be implemented in anyenvironment. The figure also shows a binary phase diagram, where thex-axis is the carbon concentration in a selected metal (such as copper,as shown) as expressed in atomic percent. The temperatures in thetemperature profile in the figure as also shown in the phase diagram.Various metals can be used (such as silver, tin, etc.). In some cases,alloys are formed.

A general idea behind the growth of single layer graphene (SLG) or fewlayer graphene (FLG) on molten metal is to dissolve carbon atoms insidea transition metal melt at a certain temperature, and then allow thedissolved carbon to precipitate (referring to the creation of a solidfrom a solution) out at lower temperatures.

The schematic depicts graphene growth from molten nickel by (forexample): (1) melting nickel while in contact with graphite (as carbonsource), (2) dissolving the carbon inside the melt at high temperatures,and (3) reducing the temperature for growth of graphene.

As depicted, keeping the melt in contact with a carbon source at a giventemperature will give rise to dissolution and saturation of carbon atomsin the melt based on the binary phase transition of metal-carbon. Uponlowering the temperature, solubility of the carbon in the molten metalwill decrease and the excess amount of carbon will precipitate on top ofthe melt.

FIG. 11 is a cross-section view of a (conventional) plasma flameapparatus 1100. The figure is being presented to distinguish uses of alegacy plasma flame apparatus as compared to uses of theherein-disclosed microwave plasma torch. Specifically, although use of alegacy plasma flame apparatus can produce diamond, or diamond-likematerials on the surface of metals, the process requires significanttime for material dissolution of carbon and diffusion so that the finalmaterials precipitate out onto the surface of the metal. During thecreation of metal-carbon composite materials as disclosed herein withthe presently disclosed implementations, graphene is desired to beinterstitially grown and locked between layers (or within lattice ormatrix sites) of metals or metal-containing composite materials.However, to do so, the temperatures must be modulated at a high rate.Unfortunately, legacy plasma torches do not offer sufficient controlover the temperature and other conditions that are needed to reduce thesize of interstitial carbon structures to the nanometer scale (as may bedesirable in connection to achieving the covetic materials as desiredherein).

In contrast, a pulsed microwave reactor (as relevant to the presentlydisclosed implementations as introduced earlier) and correspondingprocesses are shown and described in FIG. 12 to offer sufficientdetailed control over the temperature and other conditions that areneeded to reduce the size of interstitial carbon structures to thenanometer scale.

FIG. 12 depicts a pulsed microwave process flow 1200 that is used when“growing” graphene, referring to the layer-by-layer systematicdeposition or application of graphene on substantially flat exposedsurfaces of molten metal particles. As an option, one or more variationsof pulsed microwave process flow 1200 or any aspect thereof may beimplemented in the context of the architecture and functionality of theimplementations described herein. The pulsed microwave process flow 1200or any aspect thereof may be implemented in any environment.

When using the shown pulsed microwave process flow 1200, graphene isgrown onto small molten particles. This is accomplished by interactionswithin the pulsed microwave reactor that occur around inlet 1204 (suchas where the metal powder and carrier gas are inlet into the reactorchamber). In addition to inlet 1204, a process gas port 1202 andadditional ports (such as additional port 1203 ₁ and additional port1203 ₂) are provided at different heights on the side of the reactorapparatus. A waveguide traverses at least the distance from the positionof the process gas port 1202 on the side of the reactor to the positionof the inlet 1204 on the side of the reactor. Details of how to make anduse ports for introduction and continued supply of material into such areactor for growing graphene onto small molten particles are furtherdisclosed below. More specifically, certain components of the reactor ofFIG. 12 are shown and described as pertains to FIG. 13 .

FIG. 13 is a perspective view of a conventional pulsed microwave plasmaspray waveguide apparatus 1300 that is used for growing graphene ontosmall molten particles. As an option, one or more variations of pulsedmicrowave plasma spray waveguide apparatus 1300 or any aspect thereofmay be implemented in the context of the architecture and functionalityof the implementations described herein. The pulsed microwave plasmaspray waveguide apparatus 1300 or any aspect thereof may be implementedin any environment.

In this implementation, microwave delivery components and a pulsingpower supply are integrated to form a “surfaguide” (or the like) gasreactor. As shown, a combination of these components is configured tofacilitate growing graphene onto small molten particles using amicrowave plasma torch.

An alternative approach is to perform micro-welding using a tungsteninert gas (TIG) plasma source to partially or entirely melt the metal.Such a micro-welding technique is shown and described as pertains toFIG. 14 .

FIG. 14 is a schematic depiction of a micro-welding technique 1400 thatis used for growing graphene onto small molten particles. As an option,one or more variations of micro-welding technique 1400 or any aspectthereof may be implemented in the context of the architecture andfunctionality of the implementations described herein. The micro-weldingtechnique 1400 or any aspect thereof may be implemented in anyenvironment.

A low power, low flow TIG welder power supply and control unit with acustom plasma containment section can be effectively used to heat metalparticles of all types. As shown, the exhaust plume, when inserted intothe surface wave plasma gas dissociation tube, allows temperatures toremain high enough for the growth of graphene. This mode of growthinvolving control of plasma radicals composed of hydrocarbons and otheradded gases formed under non-equilibrium conditions provides many tuningopportunities that can be exploited by many different configurations ofa microwave plasma spray apparatus. FIG. 15 , FIG. 18A1, FIG. 18A2, FIG.18B, FIG. 18C, and FIG. 18D, as well as other figures and correspondingwritten description disclose example configurations of plasma sprayapparatus.

FIG. 15 is a schematic depiction of a plasma spray apparatus in acoaxial configuration 1500. As an option, one or more variations ofcoaxial configuration 1500 or any aspect thereof may be implemented inthe context of the architecture and functionality of the implementationsdescribed herein. The coaxial configuration 1500 or any aspect thereofmay be implemented in any environment.

In a coaxial style implementation, microwave energy delivery is achievedvia TEM waves fed into an antenna with the outer portion of the coaxialmember being a quartz tube outside of which are flowed powdered metallicparticles. The gas that is fed into the center region in this example isa hydrocarbon gas such as methane, where it absorbs the microwaveradiation. The powder is heated by microwave energy that escapes thecentral region and by external inductive heating, which causes metalpowder (in particulate form) to melt near the inclined portion, or tip,of the displayed reaction chamber. As the CH₄ decomposes (into itsconstituent species, carbon, hydrogen, and/or derivatives thereof),carbon radicals nucleate on the surface of the melted metal droplets viathe energy of the plasma radicals. Tuning of the microwave duty cycle,as well as tuning of the inductive heating, as well as tuning of theplasma characteristics, facilitates maintenance of differenttemperatures between the melt and the plasma decomposition/ionizationregion. Moreover, the non-equilibrium temperature allows for(facilitates) internal lattice placement of the graphene/carbon, andquick quenching creates conditions conducive to further coveticmaterials growth.

FIG. 16 is a schematic depiction of a plasma spray apparatus 1600showing the evolution of materials by processing through a series ofnon-equilibrium energy conditions. As an option, one or more variationsof the plasma spray apparatus 1600 (or any aspect thereof) may beimplemented in the context of the architecture and functionality of theimplementations described herein. The plasma spray apparatus 1600 or anyaspect thereof may be implemented in any environment.

The figure depicts evolution of materials as they pass through theapparatus. Specifically, the figure depicts the regions where differentevolutionary changes occur such that in the region near the tip,graphene is grown onto the small metal melt particles. This material isdeposited onto a substrate.

FIG. 17 depicts a surface wave plasma system 1700 for growing grapheneonto molten particles. As an option, one or more variations of thesurface wave plasma system 1700 or any aspect thereof may be implementedin the context of the architecture and functionality of theimplementations described herein. The surface wave plasma system 1700 orany aspect thereof may be implemented in any environment.

In the shown configuration, the supply gas is fed into the center regionof the apparatus. In this example a hydrocarbon gas such as methane isused. The hydrocarbon gas absorbs the microwave radiation, whichprovides a heat source to heat metal powder. Thus, the metal powder isheated from both: (1) the microwave energy that escapes the centralregion; and, (2) the external inductive heating, to melt and becomemolten near the tip. As the hydrocarbon gas decomposes, carbon radicalsnucleate on the surface of the melted metal droplets via the energy ofthe plasma radicals.

FIG. 18A1 depicts an axial field configuration 1810 of a plasma spraytorch. The formation of covetic materials has been discussed usingseveral different apparatuses and corresponding processes. Any of theforegoing apparatuses and corresponding processes can be tuned toachieve particular conditions for formation of covetic materials. In thespecific axial field configuration shown, the processes includegenerating an electric field 1804 between the electrodes to createcurrent flow through a melt of metallic and carbon materials.Specifically, and as shown, a specially configured plasma torch has anexternally controlled field where the melted particles form a plasma,which in turn becomes a meta electrode. The electrode on the other sideof the field is formed by the shown growth plate 1803. The coveticmaterials are accelerated through an acceleration zone 1821 and thendeposited onto a surface. The created alloy and covetic materialscontinue to be deposited onto the growth plate and/or onto previouslydeposited materials in the impaction zone 1823. This technique fordeposition results in a material where the carbon loading is homogeneousand in high concentration.

Input materials can be selected and varied so as to achieve particularproperties exhibited materials. For example, and as shown, inputs to theplasma spray torch may include various input gasses 1812 as well asinput metallics and/or carbon particles 1818. The foregoing inputs canbe introduced into one or more input ports 1862. In some cases, theinput metallics and or carbon particles are entrained within a flow ofinput gasses 1812. Furthermore, the growth plate can change itsdimension and composition during ongoing deposition. For example, and asshown, the growth plate 1803 can initially be a substrate 1816, on topof which is deposited hot covetic materials in a torch stream that atleast partially melts the substrate as the covetic materials aredeposited. The deposited hot covetic materials cool from a molten orpartially molten state to form quenched layers.

In this manner, any number of layers can be formed. The temperatures atthe substrate and/or at or near the topmost layer can be controlled suchthat when a next layer of materials lands on the molten metal of thejust formerly-deposited layer, the newly-deposited layer grows in alateral way to produce single-layer graphene on the surface of thismolten metal. This mechanism is distinguished from other techniques atleast in that, in contrast to conventional metal melt methods 103, wherecarbon precipitates out of a molten metal slurry, application of theherein-disclosed plasma spray torch methods 104 results in quenching ina short time period such that there is insufficient time for the carbonto precipitate out of the matrix. Thus, covetic bonds remain intactthroughout the layer. A few moments later, after the quenching hasformed a solid of metal and well dispersed carbon, another layer issprayed on top of that, and so on, thereby forming layers ofsingle-layer graphene that was grown, captivated and quick-quenched toproduce a true covetic material with extremely high carbon loadingwithin the matrix. As one example, when using conventional metal meltmethods 103 (see FIG. 1A), carbon loading might achieve 6% carbon metal.In contrast, when using plasma spray torch methods 104 (see FIG. 1A),60% carbon loading is readily achieved. In some cases, tight control ofinputs and process parameters of the plasma spray torch and itsenvironment allow carbon loading to approach as much as 90% carbon inthe resulting material.

Experimental results using plasma spray torches have shown that highlyloaded, highly uniform covetic layers can be formed by at least twoquick-quench (such as ‘splat’) methods. A first method brings in carbonparticles to cover metal particles (such as in the plasma) and theresulting hot mixture is sprayed onto a much cooler substrate. A secondmethod creates graphene in the plasma and then brings in molten metalthat covers the graphene. In both cases, true covetic (referring to acombination of covalent and metallic chemical) bonding occurs while inthe plasma plume, and the quick quenching of the spray serves tocaptivate the mixture into an organo-metallic lattice.

As shown in FIG. 18A2, the depth or thickness of the quenched layers1824 can be caused to be thicker or thinner by controlling distancesbetween the plasma flame 1814 and the substrate and/or by controllingthe temperatures at the substrate 1816 (such as either higher or lowerthan ambient) and/or by controlling the pressures in and around thereactor.

FIG. 18B depicts a radial field configuration 1820 of a plasma spraytorch. In this configuration, the melted particles form a plasma withinthe torch, which plasma becomes a meta electrode. The other electrode isformed by the side of the internal wall.

The foregoing configurations of FIG. 18A1, FIG. 18A2, and FIG. 18B aremerely examples. Other configurations involving different inputmaterials and different input port configurations are possible withoutdeparting from the generality of the plasma spray torch disclosedherein. Moreover, different configurations involving different inputmaterials and different input port configurations can achieve the sameintended results. For example, two different configurations that aretuned to achieve the same resultant material are shown and described aspertains to FIG. 18C and FIG. 18D. Specifically, the exampleconfigurations of FIG. 18C and FIG. 18D can be used for plasma spraytorch deposition of ceramic film materials onto carbon-containingparticles (such as graphene-containing particles).

Indeed, thin film deposition of carbon-containing materials (such as viaatmospheric pressure chemical vapor deposition (APECVD) and/or othervariations of chemical vapor deposition (CVD)) have made their way intomany areas of materials processing. Various composites and coatingsinvolving such carbon-containing materials may exhibit improved physicalproperties (such as strength, imperviousness to corrosion, etc.). Themorphological characteristics of various 2D and 3D carbons inure theseimproved physical properties to the composites and coatings by virtue ofmolecular-level configurations within the carbon-containing materials.In some cases, use of 2D and 3D carbons in composites and coatingsgreatly increases the resultant carbon-containing material'simperviousness to high temperatures; however, in some cases, these hightemperatures rise above ˜2100° C., which is high enough to burn the 2Dand 3D carbons themselves. Unfortunately, destroying the 2D carbons and3D carbons in turn destroys the benefit originally garnered by thecarbons in the composite or coating. Therefore, deposition techniques(such as plasma spray torch configurations) are needed to createcomposites or coatings that are impervious to temperatures even higherthan the combustion temperature of carbon.

FIG. 18C depicts such a configuration, strictly as a non-limitingexample. By tuning the inputs and various in-reactor conditions,graphene-containing materials can be coated with a heat-absorbing layerof organically modified silicon (ORMOSIL). The deposition of ORMOSILceramic materials onto graphene-containing materials can be achieved viaseveral methods including through the process of atmospheric, reactiveplasma-enhanced chemical vapor deposition using a silicon-containingprecursor 1841 (such as hexamethyl di-siloxane) and a reactive gas suchas oxygen. This particular mixture of the silicon-containing precursorand oxygen is made reactive within the plasma. The moleculardissociation that occurs within the plasma flame leads to deposition ofsilicon oxide onto surfaces such as the foregoing growth plate 1803. Toaccomplish this, in-reactor conditions are controlled such that anorganically modified silicon ceramic is deposited onto surfaces ofcarbon-containing particles as they form in the reactor. Control ofin-reactor growth and in-reactor deposition (such as by controllingAPECVD processes) leads to a thin quartz coating around thecarbon-containing particles, which are in turn deposited onto asubstrate. The thin quartz coating acts as a flame-retardant layer toprotect the carbon-containing particles from burning at elevatedtemperatures.

FIG. 18D depicts an alternative configuration, strictly as anon-limiting example. As shown, metallic and/or carbon-containingmaterials are input into the reactor. Microwave energy 1822 iscontrolled to achieve at least the temperature to dissociate thecarbon-containing materials (such as T(c-dis) of FIG. 10 ). Asilicon-containing precursor 1841 (such as HMDSO, HMDSN, etc.) isintroduced into the plasma flame and the temperature is lowered in theplasma afterglow. As the temperature is lowered, carbon particles beginto form, becoming coated with the silicon oxide. The carbon particlescoated with the silicon oxide are then deposited onto a substrate.

In one implementation, a thin layer of perhaps 10 nm thick of these 3Dmaterials can be deposited onto a substrate, which won't burn or catchfire even at 1200° C. This is because pristine carbon (such as graphene)is crystallized, such as it's not an amorphous material. Rather, it hasbeen reduced to a state where it simply won't burn anymore.

On one use case, the foregoing plasma spray torch techniques can be usedto produce new types of solder that is non-eutectic. Or, as another usecase, the plasma spray torch can spray a coating of material directlyonto a substrate to prevent the underlying material from oxidizing.

In addition to forming materials that do not combust even at 1200° C. inatmospheric pressures, putting quartz around materials often yields hugeadvantages in applications.

Besides organically modified silicon, other organic substances can beused to coat the carbon particles or the carbon layers. Characteristicsof the coating can be controlled. As one example, the pores of thesurface of the sprayed-on materials can be tuned to be hydraulicallysmooth.

A plasma spray torch can be used to form a heat-absorbing, glass-coated,non-flammable graphene composed of graphene and silicon, where thesilicon coats the graphene such that the graphene is able to withstandtemperatures higher than 1600° C. Such a heat-absorbing, glass-coated,non-flammable graphene absorbs infrared energy.

One specific method for producing organically-modified silicon coatingscomprises steps of (for example): (1) introducing a silicon-containingprecursor into a plasma spray torch apparatus, (2) combining thesilicon-containing precursor with a carrier gas having carbon particlesthat are entrained in the precursor gas, and (3) coating the carbonparticles with silicon.

The characteristics of the flame-retardant and infrared obscurantmaterials that result from the plasma spray torch configuration of FIG.18C and/or FIG. 18D can be tuned, at least in part, by controlling thetime-temperature paths though the reactor. More generally, thecharacteristics of materials that result from the plasma spray torchconfiguration of FIG. 18A1, FIG. 18A2, FIG. 18B, FIG. 18C or FIG. 18Dcan be tuned, at least in part, by controlling (such as pulsing) themicrowave energy within the reactor.

FIG. 19 is a chart 1900 that depicts energy versus time during pulse onand pulse off. More specifically, the chart shows one complete timecycle, from time T=0 through 50 microseconds with the microwave beingcontinuously turned on, and then the remaining portion of the showncycle depicts a time with the microwave being turned off. The plottedcurves depict (1) changing density, and (2) changing temperature overthe cycle. At time T=0, the temperature is at a minimum point (such asdepicted at the origin of the chart). The temperature rises rapidly,then decreases, during which time the plasma density reaches arelatively stable value. When the microwave is turned off at time T=50microseconds, both the plasma density and the temporal electrontemperature decrease rapidly. The pulse time and duty cycle can becontrolled so as to achieve a particular density and temperature at anypoint in time.

FIG. 20A1 depicts images that show organo-metallic bonding that occurswhen combining carbon and copper using a plasma spray torch. As shown,carbon 2052 is deeply embedded within copper 2054. As commonlyunderstood and as referred to herein, organometallic chemistry impliesthe study of organometallic compounds, chemical compounds containing atleast one chemical bond between a carbon atom of an organic molecule anda metal, including alkaline, alkaline earth, and transition metals, andsometimes broadened to include metalloids like boron, silicon, and tin,as well. Aside from bonds to organyl fragments or molecules, bonds to‘inorganic’ carbon, like carbon monoxide (metal carbonyls), cyanide, orcarbide, are generally considered to be organometallic as well. Relatedcompounds such as transition metal hydrides and metal phosphinecomplexes may be included in discussions of organometallic compounds,though strictly speaking, they are not necessarily organometallic.

Within organometallic chemistry, organocopper compounds contain carbonto copper chemical bonds, and may possess unique physical properties,synthesis, and reactions. Organocopper compounds may be diverse instructure and reactivity but remain somewhat limited in oxidation statesto copper(I), such as denoted Cu⁺. As a d¹⁰ metal center, it is relatedto Ni(0), but owing to its higher oxidation state, it engages in lesspi-backbonding. Organic derivatives of Cu(II) and Cu(III) may be invokedas intermediates but are rarely isolated or even observed. In terms ofgeometry, copper(I) adopts symmetrical structures, in keeping with itsspherical electronic shell. Typically, one of three coordinationgeometries may be adopted: linear 2-coordinate, trigonal 3-coordinate,and tetrahedral 4-coordinate. Organocopper compounds form complexes witha variety of soft ligands such as alkyl phosphines (R₃P), thioethers(R₂S), and cyanide (CN⁻).

By any one or more of the aforementioned techniques, the carbon depictedin FIG. 20A1 and FIG. 20A2 is chemically bonded to copper—as opposed tomerely being juxtaposed to copper to adhere thereto via van der Waalsforces (such as referring to a distance-dependent interaction betweenatoms or molecules). Unlike ionic or covalent bonds, van der Waalsattractions do not result from a chemical electronic bond; they arecomparatively weak and therefore more susceptible to disturbance.Moreover, the van der Waals forces quickly vanish at longer distancesbetween interacting molecules. Instead, what is desired isorgano-metallic bonding between a metal and carbon.

FIG. 20A2 depicts images that are a graded composition of matter appliedinto a substrate material and showing three material property zones. Thebulk metal zone 2066 is a first material property zone of these threematerial property zones. As shown, the first material property zonecomprises a metal in a first crystallographic formation, the firstcrystallographic formation having substantially metallic bonds betweenmetal atoms present in the first material property zone. This firstmaterial property zone is substantially adjacent to a second materialproperty zone that at least partially overlaps the first materialproperty zone. The covetic material zone 2064 comprises at least somecarbon atoms in a second crystallographic formation, wherein the secondcrystallographic formation has at least some covalent bonds between someof the carbon atoms that are present in the second material propertyzone and the metal atoms that are present in the first material propertyzone. The top surface zone 2062 is a third material property zone thatat least partially overlaps the second material property zone. This topsurface zone comprises further carbon atoms that are oriented in a thirdcrystallographic formation. The third crystallographic formation ischaracterized as having at least some covalent bonds between individualones of the further carbon atoms that are present in the third materialproperty zone. In various implementations, there may be some metal atomsin any of the zones, and there may be some carbon atoms in any of thezones however, this implementation is characterized by a higher metalcontent zone 2074 that is adjoining to the bulk metal zone 2066. Invarious implementations, here may be some carbon atoms in any of thezones, and there may be some metal atoms in any of the zones however,this implementation is characterized by a higher carbon content zone2072 that is adjoining to the top surface zone 2062.

FIG. 20B is a materials evolution chart 20B00 depicting several layeredconfigurations that occur when adding carbon to bulk aluminum. In theseimplementations, materials are sprayed onto an existing, carbon richcovetic substrate or carbide layer to create a carbon to carbon bondthrough carbon sintering and/or metal melt encapsulation, which in turncreates attachments to form a composite film. The materials evolutionchart 20B00 is merely one example of a combinational material (siliconcarbide) that is sprayed onto an aluminum bulk material. The process canbe tuned to create a covetic or covetic-like film that is deposited ontobulk materials. The resulting materials then can be coated to create afunctionalized top layer. One possible configuration of an apparatus forspraying combinational material onto substrate is given in FIG. 21A.

FIG. 21A depicts an apparatus for spraying a molten mixture of materialsonto a substrate. The figure depicts a microwave reactor that comprisesmultiple regions inside a containment vessel. Pulsed microwave energyfrom microwave energy source 2117 operatively coupled to the reactor isdelivered into the containment vessel. A hydrocarbon process gas 605 isprovided through an inlet port. The microwave energy heats the processgas to a high enough temperature to form plasma. The expansion ofmaterials within the containment vessel creates a plasma plume. Thecontinuous addition of materials into the containment vessel incombination with the aforementioned expansion results in a torch effectin and around the plume. Resulting from the high temperatures within andaround the plasma plume, the carbon dissociates from the hydrogen, thusforming several different hydrocarbon species (such as CH₃, CH₂). As thetemperature continues to increase (such as in the first region 2104, asshown), all or nearly all of the carbon atoms become dissociated fromthe hydrogen. Using any known technique (such as using a gas-solidseparator), the hydrogen-only species are separated from the solidcarbon species.

At the interface between the first region 2104 of the containment vesseland the second region 2106 of the containment vessel, molten metal ormolten metal composite, or molten ceramic-metal, or metal matrix, ormetal mixture of any sort is introduced through a second inlet into thecontainment vessel (as shown). The location of the second inlet isselected based on the dimensions of the plasma plume, and/or thetemperature of the molten metal at the point of inlet into thecontainment vessel. More specifically, the metal melt 2108 is introducedinto the reactor at a location where the molten metal mixes with thecarbon species. As the mixture flows (such as at a high rate ofvelocity) through the containment vessel, the mixture cools to a lowertemperature. The flowing mixture exits the containment at a high rate ofvelocity such that the mixture of carbon and molten metal is sprayed outof the exit port 2110. The mixture is deposited (such as via sprayingsprayed material 2112) onto a target substrate 2116. Various mechanismsfor controlling the uniformity of the sprayed material 2112 and/or theresulting deposited material 2114 are shown and discussed as pertains toFIG. 23A through FIG. 23D.

The temperatures in the second region are low enough that at least someof the carbon precipitates out of the mixture. However, most of thedissociated carbon remains in mixture with the molten metal. When themolten metal mixed with the carbon reaches the target substrate 2116, itcools into a solid. During the transition from a molten mixture to asolid deposit, carbon is trapped between layers of metal and carbon. Atcertain temperatures the carbon forms covalent bonds with the metal,thus resulting in covetic material. This covetic material exhibits arange of mechanical, thermal, electrical and tribological properties dueto increased cohesion forces (such as covalent bonds) between the metalmatrix and carbon.

Such covetic materials are a result of use of the pulsed microwaveenergy to control the energy distribution of the constituents of thematerials in the first region and second region of the reactor. Morespecifically, the energy distribution of the constituents of thematerials in the first region and second region of the reactor can becontrolled in part by pulsing the microwave and in part by pre-meltingthe metal particles in an environment external to the chamber of thereactor (such as so as to introduce fully-melted or partially meltedmetal into the reactor chamber). Any known techniques can be used,singly or in combination to melt the metal particles. As such the degreeand/or mixture of fully melted or partially melted particles can becontrolled.

FIG. 21B depicts a method for spraying covetic materials onto asubstrate. The method can be used in conjunction with the apparatus ofFIG. 21A. As shown, the method is performed using a microwave reactorhaving an inlet for a process gas, an inlet for a metal melt, and anexit port. Prior to operation, the microwave reactors configured(operation 21B02). At operation 21B10, the inlet serves to introduce ahydrocarbon process gas into a first region of the reactor. Using themicrowave energy, the temperature in the first region of the reactor iselevated such that the hydrocarbon process gas dissociates into carbonand hydrogen species before reaching the metal melt. A different inletserves to introduce a metal melt into a second region of the reactor(operation 21B20). The elevated temperature in the second region ismaintained until the dissociated carbon mixes with the metal melt(operation 21B30). The effect of the aforementioned plume operates tomove the mixture into a third region of the reactor (operation 21B40).Movement away from the microwave energy source has the effect ofreducing the temperature of the mixture until at least some of thecarbon condenses out of the mixture (operation 21B50). However, eventhough the temperatures are reduced, the plasma torch effect serves tomove the mixture through the exit port at a high rate of velocity(operation 21B60). As such, the molten mixture is sprayed onto asubstrate (operation 21B70).

FIG. 21C is a schematic depicting a plasma spray process that is usedfor spraying a film. As shown, carbon radicals, polycyclic aromatics,graphene sheets, and metal particles are mixed at high temperatures in aplasma reactor (such as referring to the shown first region 2104).Nucleation occurs at these high temperatures, and as temperatures insidethe reactor decrease (such as referring to the shown second region2106), growth and assembly begins. One possible growth mechanism isdepicted by the sub-micron sized aluminum particles being coated by fewlayer graphene. These sub-micron sized aluminum particles are heldtogether with a combination of metallic bonds, covalent bonds andcovetic bonds. More specifically, and as shown at the 2 nm scale, carbonatoms are bonded to aluminum atoms. The carbon atoms are organized intoa coherent graphene plane that is situated in the aluminum matrix. Theforegoing discussion involving aluminum is merely an example. Othermetals can be used. In fact, a coherent graphene plane can be situatednot only in a face-centered cubic (FCC) metal lattice, but also in abody-centered cubic (BCC) metal lattice, or in a hexagonal close packed(HCC) metal lattice.

The foregoing coated particles are then sintered to form particles thathave diameters on the order of 100 microns. These semi-molten particlesare then accelerated through the reactor and impacted onto a substrate(such as in a first pass), or onto a previously deposited layer ofimpacted particles (such as in a second or Nth pass).

FIG. 22A depicts an apparatus for wrapping carbon particles with amolten metal. The configuration of the apparatus of FIG. 22A differsfrom the configuration of the apparatus of FIG. 21A at least in that theintroduction of the molten metal is controlled using the meltingapparatus 2209. The metal melt is controlled so as produce molten metalthat wraps around carbon particles when the molten metal is introducedinto the reactor.

FIG. 22B depicts a method for wrapping carbon particles with a moltenmetal. The method differs from the method of FIG. 21B at least in that,in operation 22B30, the temperatures in the different regions of thereactors are maintained such that some carbon particle species form fromthe dissociated carbons. In operation 22B50, at least some of thosecarbon particles become wrapped by the molten metal. Some bonds areformed between constituent atoms of the carbon particles and atoms ofthe metal melt. In operation 21B60, the metal-wrapped carbon particlesmoved through the exit port, further reducing the temperature. When themetal-wrapped particles are deposited onto the substrate (operation21B70) further bonds are formed between the metal-wrapped carbon and themetal of the substrate.

FIG. 23A, FIG. 23B, FIG. 23C, and FIG. 23D depict example depositiontechniques, according to some implementations.

As shown in FIG. 23A, the deposited material has a curved shape that ischaracterized by a middle region of a higher height and end regions of alower height. In some cases, this is a desired shape for a spot ofdeposited material. In other cases, it is desirable to spray depositedmaterials over larger areas. This can be accomplished by moving thesubstrate with respect to the spray, or by moving the spray with respectto the substrate. FIG. 23B depicts a flexible substrate 2310 that isdispositioned onto a supply reel. The flexible substrate can be drawnonto and around a take-up reel. As such, and in the configuration ofFIG. 23B, the spray deposits covetic materials uniformly onto the movingsubstrate. When the relative movement between the sprayed material 2112and the substrate is controlled, the resulting deposited materials areof uniform thickness.

In some situations, it is desired to have a non-flat, but uniformpatterning at the surface of the deposited materials. In such asituation, the movement of the substrate can be stepped through a seriesof discrete positions, thus resulting in the patterning of FIG. 23C.Additionally, or alternatively, a slotted antenna can be disposedbetween the sprayed material 2112 and the substrate. The slotted antennafunctions by distributing the spray evenly across the lateral distanceof the slotted antenna. Using such a slotted antenna, a single spot ofsprayed material 2112 can have thickness and surface uniformitysubstantially as shown in FIG. 23D.

FIG. 24A and FIG. 24B depict conventional techniques for deposition ofmaterials onto a substrate. As shown in FIG. 24A, a carbon agglomerationis held together through use of a binder (such as polymerics). Thisresults in weak binding at the interface between the carbonagglomeration and the substrate. FIG. 24B depicts a coating of carbonmaterials onto a substrate using a binder. Conventional deposition usingbinders suffers from peeling. Moreover, even when the surface of thesubstrate is mechanically pretreated and/or pretreated with depositionof binder material, the interactions between the substrate and thecarbon agglomeration are weak.

As heretofore described, coatings based on deposition of materials ontoa substrate using binders and/or using coating techniques (such as suchas are shown and described as pertains to FIG. 24A and FIG. 24B) sufferfrom peeling, low strength properties and other undesirable mechanicalproperties. Improvements based on plasma spray techniques are shown anddiscussed in FIG. 25A and FIG. 25B.

FIG. 25A and FIG. 25B depict example deposition techniques that resultin covalent bonding at the surface of a substrate, according to someimplementations. Specifically, and as shown, when the herein-disclosedtechniques are used, covetic materials are formed by covalent bondsbetween the carbon and the substrate. As such, no binder is needed orused. Furthermore, many of the bonds formed at the interface between thesubstrate and the covetic material are strong covalent bonds. In onespecific case, where the substrate is aluminum, covalent bonds areformed between atoms that are in the face-centered cubic structure ofaluminum and atoms of carbon that are in a hexagonal structure. Aschematic of interfacial bonding is depicted in FIG. 25B.

FIG. 26A, FIG. 26B, FIG. 26C, and FIG. 26D present schematic diagramsthat depict how covalent bonds are formed between sites in the squareshapes of a face-centered cubic structure of aluminum and sites in thehexagonal shapes that occur in certain crystallographic structures ofcarbons.

FIG. 26A is an orthogonal view showing the square shapes offace-centered cubic structure of aluminum. FIG. 26B is an orthogonalview showing the hexagonal shapes that occur in certain crystallographicstructures of aluminum.

FIG. 26C depicts one possible superposition of the hexagonal shapes thatoccur in certain crystallographic structures of carbons on top of thesquare shapes of face-centered cubic structure of aluminum. FIG. 26Ddepicts covalent bonds that are formed at certain sites. The example ofthe face-centered cubic structure of aluminum is merely one example.Other metals having other crystallographic structures are possible.

FIG. 26E is an example of a layered covetic material 26E00, where agraphene-like structure is sandwiched between layers of metal material.The lower layer of metal material is a layer of substrate. The top layerof metal material is formed of quenched material that was formerlymolten while in the reactor. The graphene-like structure that issandwiched between layers of metal material is captured between the twolayers of metal due to the formation of metal-to-metal bonds between thetwo metal layers. In addition to the metal bonds, other bods are formedthat serve to encase the graphene-like material between the metallayers. In some locations, there are defects in the carbon lattice.Various types of bonds are formed between or near such defects.

Any or all of the foregoing techniques for forming covetic materials canbe used in many applications involving many different types ofsubstrates. Moreover, the relative movement between the spray and thesubstrate can be controlled so as to result in deposits of anythickness. Any known techniques can be used to control the relativemovement. For example, the exit port can be moved over a stationarysubstrate. This can be accomplished using a hand-held device or arobotically controlled device that is moved relative to the stationarysubstrate. In some cases, the substrate can be subjected to a biasvoltage such that at least some of the material that is sprayed out ofthe exit port is electrostatically attracted to the surface of thesubstrate. This has applicability in applications where the substrate isnot uniformly flat. As examples, applications where the substrate is notuniformly flat may include: (1) shaped components that are used inmachinery that is subjected to corrosively harsh conditions, (2) turbineblades, (3) heat exchanger components, etc., many of which applicationsare further discussed infra.

In other situations, characteristics (such as thickness, lateraluniformity, etc.) of the deposition can be enhanced through use ofand/or combinations of various chemical vapor deposition techniques.Strictly as one example, aspects or parameters pertaining toknown-in-the-art plasma enhanced chemical vapor deposition techniquescan be controlled so as to optimize characteristics of the depositedlayers of covetic materials. As another example, rather than depositingcovetic materials onto a surface to form a film or coating, coveticmaterials can be formed into particles (such as by spraying into a lowertemperature environment) and collecting the particles as a powder.Various techniques involving production and use of powered coveticmaterials are briefly discussed hereunder.

Powdered Covetic Materials

In some situations, rather than forming covetic materials as a film orcoating on or in a substrate, covetic materials can be delivered as acovetic material powder. Such a powdered covetic material can becollected as it exits the reactor, cooled to a temperature below themelting point of the covetic material and collected as a powder. Thepowder in turn can be handled (such as stored and shipped, poured,mixed, etc.) at room temperatures. The powder can then be remelted andpressed into a form or remelted and re-sprayed. As examples, componentsfor use in highly corrosive environments can be formed from suchpowdered covetic materials using injection molding or extrusion. Manyapparatuses can be used, singly or in combination to form and transportcovetic material powders. Example apparatus are shown and described aspertains to FIG. 27A, FIG. 27B1 and 27B2.

FIG. 27A depicts an example apparatus 27A00 for producing powderedcovetic material 2710 using a cooling region 2702 to cool the sprayedmaterial 2112 when the spray is forced through an exit port 2110 of amicrowave reactor. Any one or more cooling techniques in any combinationcan be used to lower the temperature of the covetic material in coolingregion 2702 to a temperature that is lower than the melting point of thecovetic material. The cooling region 2702 might host one or moreapparatuses to cause the cooling. For example, and as shown, acollection vessel 2704 might be fitted with one or more apparatuses tocause a cyclone effect in the collection vessel, thereby increasing thetime for lowering the temperature of the covetic material. In somecases, the time for cooling the covetic material is controlled (such asby increasing or decreasing the time) so as to allow the coveticmaterial to anneal with highly regular bonding. In some cases,controlling the time during which the covetic material is cooled allowsfor the covetic material to crystalize into highly regular crystallinestructures, while still remaining in powered form. In someimplementations, a mechanical tumbler-agitator can be fitted between theexit port 2110 of the microwave reactor and collection vessel 2704. Thetumbler-agitator can be cleaned or replaced periodically.

Alternatively, or additionally, and in situations where it is convenientand/or necessary to contain and/or transport powdered covetic materialin a fluid, a fluidized bed apparatus can be used. For example, to avoidagglomeration of particles of the powder, the powdered covetic materialcan be held in a liquid. In some implementations, a fluidized bedapparatus can be fitted between the exit port 2110 of the microwavereactor and collection vessel 2704. One implementation of such afluidized bed apparatus is shown and described as pertains to FIG. 27B1and FIG. 27B2.

FIG. 27B1 and FIG. 27B2 depict an example fluidized bed apparatus 27B00for cooling and handling powdered covetic materials in a fluid.

As shown, the molten metal and carbon mixture is forced through the exitport of the reactor and into the top of a fluidized bed 2750. As themolten metal and carbon mixture is forced out of the exit port, it iscooled in a manner that form particles. The particles are acted on by adownward force of gravity (such as in a downward direction, as shown)while at the same time a process fluid 2754 is forced from the bottom ofthe fluidized bed to create an upward force. As such, the particlesaccelerate toward the bottom of the fluidized bed at an accelerationrate slower than that of the local gravity. The flow dynamics can bepartially modulated by the geometry of the fluidized bed. For example,and as shown, a length of the fluidized bed can form a tapered body 2762where a first end of the tapered body has a first dimension D1 and wherea second end of the tapered body has a second dimension D2, and whereinD1>D2. The temperature within various portions of the fluidized bed canbe controlled in part by power source 2752 that powers a coil (as shown)and/or by a heat source 2760 that heats process fluid 2754 before theprocess fluid enters the bottom of the fluidized bed.

The pressures and flow rates and other conditions in the fluidized bedand at the environmental interfaces of the fluidized bed serve to causethe powder and fluid mixture to behave together as a fluid. The mixtureexhibits many properties and characteristics of fluids, such as theability to free flow under gravity, and/or to be pumped using fluidhandling technologies.

In the implementation of FIG. 27B1 and FIG. 27B2, the fluidized bed hasmultiple ports that are positioned at different heights of the taperedbody. This is so that a first powder in fluid 2756 ₁ flows out at aparticular temperature/pressure, whereas a second powder in fluid 2756 ₂flows out at a second, different particular temperature/pressure. Theflows through the multiple ports can be controlled such that thecollection vessel can receive any ratio or amounts of first powder influid 2756 ₁ and second powder in fluid 2756 ₂.

Method of Forming Covetic Materials

Table 3 shows some non-limiting examples of methods for forming powderedcovetic materials.

TABLE 3 Example Methods Designation Example Method 1 Producingorgano-metallic materials after dissociation of a hydrocarbon processgas in a microwave reactor-based plasma spray torch Example Method 2Growing carbon allotropes on input particles within a microwave reactorExample Method 3 Coating input materials after dissociation ofalternative process gases in a microwave reactor-based plasma spraytorch

Example Method 1

In some implementations of method 1, structured carbons (such as carbonallotropes) are formed in a first region of a microwave reactor (such asthrough the dissociation of a hydrocarbon process gas). In a secondregion that is at a lower temperature than the first region, thestructured carbons are decorated with a metal so as to form a metalizedcarbon material (such as an organo-metallic material). The metalizedcarbon material is further cooled to a temperature below the meltingpoint of the metal. In some implementations, the metalized carbonmaterial is initially in the form of carbon particles that are decoratedwith a metal. The particles are further cooled so as to form a powder.The powder can be collected and transported to an application facility.The powder comprising metalized carbon material having covetic bonds canbe remelted and used in conjunction with any known techniques forforming a component from a powder. Strictly as examples, components canbe formed from a powder by using die pressing followed by re-melting,isostatic pressing followed by re-melting, hot forging, metal injectionmolding, laser sintering, etc.

Example Method 2

In this method 2, one or more hydrocarbon gases (or in some cases gasesand liquids) are input into the system. Strictly as examples, the gasesand/or liquids that can be input into the system include methane,ethane, methylacetylene-propadiene propane (MAPP), and hexane. In afirst region 2104 at a first temperature, the carbon atoms aredissociated from other atoms (such as dissociated from hydrogen). Amolten metal 2108 is introduced into the reactor as metal particles.Then, in a second region 2106, the carbons produced in the first regioncombine with the metal particles. The carbon can grow on the surface ofthe metal particles and/or grow within the interior of the metalparticles. In some situations, and under some conditions, the carbongrowth comprises growth of 2D carbons on or in the metal particles. Inother situations, and/or under other conditions, the carbon growthcomprises growth of 3D carbons on or in the metal particles. In any ofthe foregoing growth situations, the growth can take place to themaximum extent allowed by the lattice. For example, the molten metal canbe aluminum with a face-centered cubic (FCC) crystal structure, and thecarbon can form a solid solution with the aluminum up to a particularconcentration. In some implementations, the carbon forms a solution withthe metal up to a concentration determined by the metal properties (suchas the crystal structure) and then precipitate out of the metal-carbonsolution to form 2D or 3D carbon on and/or within the metal particles.

The growth in this method 2 is carried out under non-equilibrium thermalconditions. Specifically, various differing thermal conditions tocontrol (for example): (1) first temperatures (such as highertemperatures) in the first region that are needed to control theforegoing dissociation, and (2) second temperatures (such as lowertemperatures) in the second region to control insipient melting of metalpowders and/or the formation and properties of the metal-carbonparticles in the second region. Temperatures in these two zones can beindependently controlled. Using this method, the sprayed materials aretrue covetic materials that exhibit true covetic behaviors.

Example Method 3

In still further non-limiting examples, materials and/or coatings oninput particles can be created or deposited from mixed materials such astrimethylamine (TMA), trimethylglycine (TMG), andmethylacetylene-propadiene propane. The particles can be cooled andcollected as a powder. Some examples of particles that can be createdfrom target materials in the first zone are phased carbons, siliconcarbide, metal oxides, metal nitrides or metals. In some cases, theinput particles are metals, and compound films (such as metal oxides ormetal nitrides) are coated on the metallic input particles, while inother cases, the input particles contain compound materials and metalliccoatings are deposited on the input particles. Some examples ofparticles that can be created from input gases in the first zone arecarbon allotropes (such as innate carbons), silicons, ZnO, AlOx, andNiO.

In some implementations, gases, including various non-hydrocarbon gassesor alcohols are input into the first zone and the first zone comprises asputtering apparatus and a power supply, wherein the sputteringapparatus is configured to generate a plurality of ionic species from aselected target material. The target material and the ionic speciescombine to form a plurality of particles. The power supply can be an AC,DC, RF, or high-power impulse magnetron sputtering (HIPIMS) power supplyand can be configured to generate a plurality of ionic species from thetarget material by tuning the power, voltage, frequency, repetitionrate, and/or other characteristics of the power supply.

FIG. 27C is a schematic depicting a plasma spray process that is usedfor production of a powdered covetic material.

Powdered Material Processing Sequence

A visual representation of an example powdered material processingsequence from hydrocarbon cracking and particle nucleation (such as theshown first region 2104), to graphene growth (such as the shown secondregion 2106), cooling of the semi-molten particles (such as in the showncooling region) and collection of powdered covetic material (such as inthe collection region, and into the collection vessel 2104) is shown inFIG. 27C. Mechanisms that underlie the efficacy of the example powderedmaterial processing sequence are now briefly discussed.

In absence of a metal precursor (whether metalorganic or particle form),the microwave plasma dissociates methane to form carbon radicals (aswell as polycyclic aromatics/acetylene) that will then form few layer(FL) graphene (or stacked lamellae) structures respectively. However, inthe presence of a metal precursor in the plasma zone (such as refer tothe reactors of FIG. 21A and FIG. 22A), the metal (either frommetalorganic nuclei or particle) can serve as a seed site forheterogeneous carbon growth (such as carbon in the form of ionizedradical, graphene nuclei, or polycyclic aromatic (acetylene)).

When using metals with a low solubility, such as Al or Cu, graphenesheets can grow (such as either through adatom/monomers or as a cluster)onto the surface of the metal. Characteristics of the growth depends atleast in part on symmetry and minimization of interfacial free energy atthe metal surface. As such, carbon growth occurs at the metal particlealongside metal atom re-sputtering events at the surface to createintermixed and/or layered metal/carbon structures. As is known in theart, the radius of the metal particle (such as surface curvature), canaffect carbon solubility in the metal particle. As an example, a smallerradius (such as corresponding to higher curvature) increases thesolubility over equilibrium (at a planar surface), which increase in thesolubility can in turn impact the thickness of the graphene layers.

Once the powdered covetic materials 2710 have been collected in acollection vessel, the powdered covetic materials can be furtherprocessed using conventional techniques (such as injection moldingtechniques, other techniques using powdered metal).

Manufacturing Techniques Using Powdered Covetic Materials

FIG. 28 depicts method for making components from powdered coveticmaterials using injection molding techniques. As shown, the method isinitiated upon gathering a set of properties for a component to be usedin a particular application and/or environment (operation 2810), thenselecting a particular powdered covetic material based on at least oneof the properties for the application or environment (operation 2820).The selection may be based on desired mechanical properties for thecomponent, and/or based on desired anti-corrosive properties of thecomponent in the environments corresponding to its intended use, and/orother desired properties. The selection might be based on multipledesired properties, and in some cases a selection tool solved anoptimization problem based on a set of properties and an objectivefunction.

Once the covetic material has been selected (operation 2820), theselected powdered covetic material 2825 is melted (operation 2830) andintroduced into a mold (operation 2840). A prescribed temperature and aprescribed pressure are maintained inside the mold for a prescribedduration (operation 2850) after which duration the temperature andpressure inside the mold is brought to about 30° C. and aboutatmospheric pressure (operation 2860). The component is released fromthe mold (operation 2870) and deployed in the intended application(operation 2880).

As heretofore mentioned, the selection of a particular covetic materialmight be based on multiple desired properties, some of which propertiesmight be used as a variable of an objective function. In some cases, theselection of a particular covetic material might be based on aparticular dominant property (such as mechanical strength, weight,anti-corrosiveness, etc.). In some cases, the properties of interest areratios of other properties, such as strength to weight, specific heat toweight, etc.) In some cases, the dominant property is to be maximized(or minimized) subject to one or more constraints on other properties.

As such, powdered covetic materials can be deployed in a wide range ofapplications. In many cases, the resulting components made from powderedcovetic materials outperform components made from other materials. Someexample applications that correlate to certain dominant properties areshown and discussed as pertains to the following FIG. 29 .

FIG. 29 depicts various properties of covetic materials. The shownproperties include mechanical attributes, thermal conductivity,resistance to oxidation, durability, resistance to softening at hightemperatures, resistance to fatigue, and electrical conductivity.Individual ones and/or combinations of these parameters become dominantwhen selecting a particular covetic material for a particularapplication.

Strictly as an example, resistance to oxidation might be a dominantparameter when selecting a covetic material for use in makingcorrosion-resistant valves. As another example, when selectingparticular covetic materials to be used in the manufacture of blades foraircraft engine turbines, mechanical attributes such as astrength-to-weight ratio, subject to a strength minimum constraint mightbe a dominating mechanical attribute. The blade might also need toexhibit a very high resistance fatigue.

Typically, covetic materials exhibit not only the aforementionedproperties but also are less dense than the metal or alloy that is usedin making the covetic powder. A lower density often corresponds to alower weight for a formed component as compared with the same componentmade from the metal or alloy in absence of carbon loading. As such,truck parts (such as cab components, as shown), automobile parts (suchas doors fenders, roof panels, etc.), motorcycle parts, bicycle parts aswell as various components (such as structural members) of airbornevehicles, and/or watercraft, and/or space-based vehicles or platformscan avail of the lower weight-to-strength ratio of covetic materials ascompared with the base metals or alloys that are used in making thecovetic materials.

As another example, covetic materials often exhibit exceptional thermalconductivity such that structural members formed of covetic materialscan be used in high-temperature applications (such as heat sinks forelectronics, industrial heat exchangers, etc.).

As yet another example, covetic materials often exhibit exceptionalresistance to corrosion. More specifically, covetic laminates made usingthe foregoing techniques exhibit extremely high corrosion resistance,even at the top layer (such as at the component-to-environmentinterface). This property is of particular interest when components madewith covetic materials are subjected to harsh environments.

As a still further example, covetic materials can be tuned for surfacesmoothness. More specifically, covetic laminates made using theforegoing techniques exhibit extremely high surface smoothness. Thissurface smoothness property is of particular interest when the coveticmaterials serve as a heat shield, such as may be demanded inapplications where friction at the surface (such as friction generatedas a fluid passes over the surface at high speed) generates unwantedheat at the surface. By using the herein-disclosed techniques, thespecific composition of the covetic material and/or by using theherein-disclosed specific techniques for deposition of the coveticmaterial can result in a hydraulically smooth surface, which can in turnbe used in airborne and/or space-based vehicles.

In certain implementations, one set of properties may dominate otherproperties. For example, the surface of a space-based vehicle (such as asatellite) might be required to be substantially non-reflective to arange of electromagnet radiation (such as substantially non-reflectiveto visible light), while at the same time, the surface of thespace-based vehicle might be required to be thermally isolating (such asthermally non-conducting). The foregoing tuning techniques accommodatesuch situations where a particular desired property (such asnon-reflectivity) dominates the tuning of the plasma spray torch so asto produce a substantially non-reflective surface, even at the expenseof other properties.

The properties as shown and described as pertains to FIG. 29 are merelyexamples. Additional properties and/or combinations of properties mightbe demanded or desirable in various applications, and these additionalproperties are exhibited in resultant materials based on tuning ofinputs and controls of the plasma spray torch. Strictly as examples ofthe foregoing additional properties, such properties and/or combinationsof properties might include or be related to a strength-to-weightmetric, and/or a specific density, and/or mechanical toughness, and/orsheer strength, and/or flex strength, etc.

In the foregoing specification, the disclosure has been described withreference to specific implementations thereof. It will however beevident that various modifications and changes may be made theretowithout departing from the broader spirit and scope of the disclosure.For example, the above-described process flows are described withreference to a particular ordering of process actions. However, theordering of many of the described process actions may be changed withoutaffecting the scope or operation of the disclosure. The specificationand drawings are to be regarded in an illustrative sense rather than ina restrictive sense.

What is claimed is:
 1. A reactor including: a first inlet through whicha hydrocarbon gas flows into the reactor; an inner tube disposed influid communication with the first inlet and configured to dissociatethe hydrocarbon gas into a plasma based on microwave energy, the plasmaincluding carbon and carbon radicals; an annular region disposed betweenthe inner tube and a reactor wall; a second inlet disposed incommunication with the annular region and configured to receive metalparticles entrained in a carrier gas; and an inductive heater disposedin thermal communication with the reactor and configured to melt themetal particles.
 2. The reactor of claim 1, further including a contactregion disposed near an outlet of the reactor and configured to producecarbon-metal composites by contacting the melt and the plasma.
 3. Thereactor of claim 2, wherein the carbon-metal composites includealternating graphene-metal layers organized according to a crystalconfiguration of the metal particles.
 4. The reactor of claim 2, whereina carbon loading in the carbon-metal composites is approximately 60%. 5.The reactor of claim 2, wherein a carbon loading in the carbon-metalcomposites is between about 60% and 90%.
 6. The reactor of claim 2,further including an acceleration zone configured to accelerate a flowof the carbon-metal composites through the outlet.
 7. The reactor ofclaim 6, wherein the acceleration zone is further configured to quenchthe carbon-metal composites.
 8. The reactor of claim 6, furtherincluding a substrate upon which the carbon-metal composites are cooled.9. The reactor of claim 2, further including a secondary apparatusdisposed downstream of the outlet, the secondary apparatus including oneor more of a cyclone reactor, a mechanical tumbler agitator, or afluidized bed reactor.
 10. The reactor of claim 9, wherein the secondaryapparatus is configured to cool the carbon-metal composites.
 11. Thereactor of claim 1, wherein the microwave energy includes pulsedmicrowave energy.
 12. The reactor of claim 11, wherein the pulsedmicrowave energy is associated with transverse electromagnetic wavepropagation.
 13. The reactor of claim 11, wherein the pulsed microwaveenergy is associated with transverse electric wave (TE) propagation. 14.The reactor of claim 11, wherein the reactor is configured to tune oneor more of a duty cycle of the pulsed microwave energy, or a power levelor duty cycle of the inductive heater.
 15. The reactor of claim 1,wherein the inner tube comprises a dielectric tube.
 16. The reactor ofclaim 15, wherein the dielectric tube includes a quartz tube.
 17. Thereactor of claim 1, wherein the reactor is configured to control thetemperature of the metal particles entrained in the carrier gasindependently of the plasma temperature.
 18. The reactor of claim 1,wherein the metal particles include one or more of aluminum, copper,nickel, copper, gold, zinc, tin, lead or silver.
 19. The reactor ofclaim 1, wherein the metal melt includes one or more of fully-meltedmetal or partially melted metal.
 20. The reactor of claim 1, wherein themetal melt includes metal melt droplets.